Visualising Recamán's sequence using TikZ

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











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I am trying to visualise Recamán's sequence using semicircles. This is an example of what I'm trying to replicate:



enter image description here



By manually defining each semicircle, I've got this so far:



enter image description here



documentclass[tikz,margin=0.5cm]standalone
begindocument
begintikzpicture
draw [line width=3mm] (0,0) arc (-180:0:1/2) arc (180:0:2/2) arc (-180:0:3/2) arc (-180:0:-4/2) arc (-180:0:5/2) arc (180:0:6/2) arc (-180:0:7/2) arc (-180:0:-8/2) arc (-180:0:9/2) arc (-180:0:-10/2);
endtikzpicture
enddocument


Is there a way to code this so it will automatically generate N iterations of the sequence?



In basic terms, the size of the steps increases sequentially, but you subtract if you can (i.e. if you arrive at a number that hasn't been used before), otherwise you add.



enter image description here



For reference, this sequence is A005132 on 'The On-Line Encyclopedia of Integer Sequences' - https://oeis.org/A005132







share|improve this question






















  • At pag.21 of the animate manual there is a 3D example with a Lorenz's fly.
    – vi pa
    Aug 25 at 13:48










  • On pag. 640 of the pgf manual there is the Fibonacci sequence.
    – vi pa
    Aug 25 at 14:29














up vote
15
down vote

favorite
2












I am trying to visualise Recamán's sequence using semicircles. This is an example of what I'm trying to replicate:



enter image description here



By manually defining each semicircle, I've got this so far:



enter image description here



documentclass[tikz,margin=0.5cm]standalone
begindocument
begintikzpicture
draw [line width=3mm] (0,0) arc (-180:0:1/2) arc (180:0:2/2) arc (-180:0:3/2) arc (-180:0:-4/2) arc (-180:0:5/2) arc (180:0:6/2) arc (-180:0:7/2) arc (-180:0:-8/2) arc (-180:0:9/2) arc (-180:0:-10/2);
endtikzpicture
enddocument


Is there a way to code this so it will automatically generate N iterations of the sequence?



In basic terms, the size of the steps increases sequentially, but you subtract if you can (i.e. if you arrive at a number that hasn't been used before), otherwise you add.



enter image description here



For reference, this sequence is A005132 on 'The On-Line Encyclopedia of Integer Sequences' - https://oeis.org/A005132







share|improve this question






















  • At pag.21 of the animate manual there is a 3D example with a Lorenz's fly.
    – vi pa
    Aug 25 at 13:48










  • On pag. 640 of the pgf manual there is the Fibonacci sequence.
    – vi pa
    Aug 25 at 14:29












up vote
15
down vote

favorite
2









up vote
15
down vote

favorite
2






2





I am trying to visualise Recamán's sequence using semicircles. This is an example of what I'm trying to replicate:



enter image description here



By manually defining each semicircle, I've got this so far:



enter image description here



documentclass[tikz,margin=0.5cm]standalone
begindocument
begintikzpicture
draw [line width=3mm] (0,0) arc (-180:0:1/2) arc (180:0:2/2) arc (-180:0:3/2) arc (-180:0:-4/2) arc (-180:0:5/2) arc (180:0:6/2) arc (-180:0:7/2) arc (-180:0:-8/2) arc (-180:0:9/2) arc (-180:0:-10/2);
endtikzpicture
enddocument


Is there a way to code this so it will automatically generate N iterations of the sequence?



In basic terms, the size of the steps increases sequentially, but you subtract if you can (i.e. if you arrive at a number that hasn't been used before), otherwise you add.



enter image description here



For reference, this sequence is A005132 on 'The On-Line Encyclopedia of Integer Sequences' - https://oeis.org/A005132







share|improve this question














I am trying to visualise Recamán's sequence using semicircles. This is an example of what I'm trying to replicate:



enter image description here



By manually defining each semicircle, I've got this so far:



enter image description here



documentclass[tikz,margin=0.5cm]standalone
begindocument
begintikzpicture
draw [line width=3mm] (0,0) arc (-180:0:1/2) arc (180:0:2/2) arc (-180:0:3/2) arc (-180:0:-4/2) arc (-180:0:5/2) arc (180:0:6/2) arc (-180:0:7/2) arc (-180:0:-8/2) arc (-180:0:9/2) arc (-180:0:-10/2);
endtikzpicture
enddocument


Is there a way to code this so it will automatically generate N iterations of the sequence?



In basic terms, the size of the steps increases sequentially, but you subtract if you can (i.e. if you arrive at a number that hasn't been used before), otherwise you add.



enter image description here



For reference, this sequence is A005132 on 'The On-Line Encyclopedia of Integer Sequences' - https://oeis.org/A005132









share|improve this question













share|improve this question




share|improve this question








edited Aug 25 at 11:54

























asked Aug 25 at 11:02









Milo

5,49821345




5,49821345











  • At pag.21 of the animate manual there is a 3D example with a Lorenz's fly.
    – vi pa
    Aug 25 at 13:48










  • On pag. 640 of the pgf manual there is the Fibonacci sequence.
    – vi pa
    Aug 25 at 14:29
















  • At pag.21 of the animate manual there is a 3D example with a Lorenz's fly.
    – vi pa
    Aug 25 at 13:48










  • On pag. 640 of the pgf manual there is the Fibonacci sequence.
    – vi pa
    Aug 25 at 14:29















At pag.21 of the animate manual there is a 3D example with a Lorenz's fly.
– vi pa
Aug 25 at 13:48




At pag.21 of the animate manual there is a 3D example with a Lorenz's fly.
– vi pa
Aug 25 at 13:48












On pag. 640 of the pgf manual there is the Fibonacci sequence.
– vi pa
Aug 25 at 14:29




On pag. 640 of the pgf manual there is the Fibonacci sequence.
– vi pa
Aug 25 at 14:29










2 Answers
2






active

oldest

votes

















up vote
21
down vote



accepted










As I am quite ignorant in TikZ I can't add the colours etc...



  • first we generate the first 1000 sequence members,


  • second, we use some kind of expandable loop in the tikz picture. For this I loaded xinttools, but there are other choices.


  • third I did three separate pictures but one can probably use in the same picture successive loops with new colors perhaps, or vary the color with index #1.


I did not abstract into a macro with the number of steps as argument, and I did not do the work to created animated gif, but this could give a start.



Also, I spend a bit time in TikZ manual looking for half-circles, but I got confused, so I stick with the arc construct of OP, I don't know if efficient or not for TikZ matters.



documentclass[tikz,margin=0.5cm]standalone

% FIRST WE GENERATE a(n) for n=0, ..., 1000
% https://oeis.org/A005132
makeatletter
@namedefrecaman00@namedefnamacer00
@namedefrecaman11@namedefnamacer11
@namedefrecaman23@namedefnamacer32
@namedefrecaman36@namedefnamacer63
% <namacerN> will give the *last* index n with a(n) = N

count@ 3
loop
advancecount@ @ne
edefzzzthenumexpr
@nameuserecamanthenumexprcount@-@ne-count@%
@namedefrecagoleftthecount@0%
ifnumzzz>z@
ifcsname namacerzzzendcsname
edefzzzthenumexprzzz+count@+count@%
else
@namedefrecagoleftthecount@1%
fi
else
edefzzzthenumexprzzz+count@+count@%
fi
expandafteredefcsname recamanthecount@endcsnamezzz%
expandafteredefcsname namacerzzzendcsnamethecount@%
typeouta(thecount@) = @nameuserecamanthecount@%
ifnumcount@<1000
repeat

usepackagexinttools

makeatletter
% I added the "recagoleft" in a second stage originally I was doing
% ifnum test to check if increase or decrease for index 2*#1 and
% 2*#1+1
% (perhaps I should have kept more cumbersome ifnum rather than
% creating these extra macros?)
defmymacro#1%
arc
if@nameuserecagoleftthenumexpr2*#11%
expandafter@firstoftwoelseexpandafter@secondoftwofi
(-180:0:-thenumexpr2*#1relax)(180:0:thenumexpr2*#1relax)%
arc
if@nameuserecagoleftthenumexpr2*#1+11%
expandafter@firstoftwoelseexpandafter@secondoftwofi
(180:0:-thenumexpr2*#1+1relax)(-180:0:thenumexpr2*#1+1relax)%

makeatother

begindocument
begintikzpicture
draw [line width=3mm]
(0,0) arc
(-180:0:1)
xintApplyUnbracedmymacroxintSeq110;
endtikzpicture
begintikzpicture
draw [line width=3mm]
(0,0) arc
(-180:0:1)
xintApplyUnbracedmymacroxintSeq130;
endtikzpicture
begintikzpicture
draw [line width=3mm]
(0,0) arc
(-180:0:1)
xintApplyUnbracedmymacroxintSeq150;
endtikzpicture

enddocument


For generating the picture I had the problem that my usual gs invocation (with transparent background) proved very slow and produced very big png's... (13M for the third one). So I did it again with smaller resolution and here is the first one (for n=2*10=20, circa).



enter image description here



For the one up to n=2*50+1=101 I upload a screen capture



enter image description here




I realized only later that 50(i.e. n=101) was maximal with 1cm units before triggering "dimension too large error" from TikZ. But this works, where the unit is about 1.5pt (2pt would be too big).



begintikzpicture[x=100000sp,y=100000sp]
draw [line width=3mm]
(0,0) arc
(-180:0:1)
xintApplyUnbracedmymacroxintSeq1499;% and not 500 as a(1001) not pre-computed
endtikzpicture


I obtain this, which indicates the values of sequence up to n=999: (sorry I initially uploaded a possibly wrong picture because I used 500, hence n=1001 but my pre-computations in preamble go only up to 1000; no error was triggered because only an if test is done about some control sequence, not a computation or an ifnum)



enter image description here




I am almost an expert in TikZ now: a draw statement can have only one colour. So I modified my approach to use some loop to accumulate multiple draw with a colour from an xcolor color series.



I wanted to create an animated gif, for this reason I do a super-loop which increases the number of steps each time. My usual convert invocation failed, using seemingly the size of the first pdf page. Then I modified the code to use the same picture size for all frames. This is why in the code below I added new macros holding max(a(n), i=0..n).



But convert again failed so I post only here a snapshot of the last frame.



But if you compile to pdf, your PDF viewer possibly with re-create the animation for you by holding down the space key (it works for me; I configured view to a single page i.e. not "continous pages").



documentclass[tikz]standalone
%usepackagexcolor
% FIRST WE GENERATE a(n) for n=0, ..., 1000
% https://oeis.org/A005132
makeatletter
@namedefrecaman00@namedefnamacer00
@namedefrecaman11@namedefnamacer11@namedefrecagoleft10
@namedefrecaman23@namedefnamacer32@namedefrecagoleft20
@namedefrecaman36@namedefnamacer63@namedefrecagoleft30
% <namacerN> will give the *last* index n with a(n) = N
@namedefrecaMax00
@namedefrecaMax11
@namedefrecaMax23
@namedefrecaMax36
count@ 3
loop
advancecount@ @ne
edefzzzthenumexpr
@nameuserecamanthenumexprcount@-@ne-count@%
@namedefrecagoleftthecount@0%
expandafterletcsname recaMaxthecount@expandafterendcsname
csname recaMaxthenumexprcount@-@neendcsname
ifnumzzz>z@
ifcsname namacerzzzendcsname
edefzzzthenumexprzzz+count@+count@%
ifnumzzz>@nameuserecaMaxthecount@
expandafterletcsname recaMaxthecount@endcsnamezzz
fi
else
@namedefrecagoleftthecount@1%
fi
else
edefzzzthenumexprzzz+count@+count@%
ifnumzzz>@nameuserecaMaxthecount@
expandafterletcsname recaMaxthecount@endcsnamezzz
fi
fi
expandafterletcsname recamanthecount@endcsnamezzz
expandafteredefcsname namacerzzzendcsnamethecount@%
typeouta(thecount@) = @nameuserecamanthecount@
(max so far=@nameuserecaMaxthecount@)%
ifnumcount@<1000
repeat

usepackagexinttools

makeatletter
defmymacro#1%
draw
[color=foo!!+]
% radius being n, width of circle 2n, end-point is at 2*a(n)
(2*@nameuserecamanthenumexpr#1-1,0)
arc
if@nameuserecagoleft#11%
expandafter@firstoftwoelseexpandafter@secondoftwofi
(unlessifodd#1 -fi180:0:-#1)(ifodd#1 -fi180:0:#1);%

makeatother

makeatletter
defdrawframe#1noexpand
draw
(0,0)--(0,-#1)--(thenumexpr2*@nameuserecaMax#1,-#1)
--(thenumexpr2*@nameuserecaMax#1,#1)--(0,#1)--cycle;%
makeatother

definecolorseriesfoorgblastbluered

begindocument

xintFor* #1 in xintSeq1100do%
begintikzpicture[x=5mm, y=5mm]
edefzzzdrawframe100zzz% get all pictures to be of same size
resetcolorseries[#1]foo%
xintApplyUnbracedmymacroxintSeq1#1
endtikzpicture


enddocument


Here is thus page 100 of the produced PDF:



enter image description here




I finally manage to get an animated gif:



enter image description here
Recipe:



  • 65 frames,


  • [x=1mm, y=1mm],

  • each draw with line width=.5mm,

  • pdflatex

  • convert -density 72 recaman-colors.pdf _tmp%02d.png

  • convert -verbose -dispose previous -loop 0 -density 100 -delay 15 _tmp00..9.png _tmp10..63.png -delay 300 _tmp64.png recaman.gif

Output not as smooth as one could hope, but 360383 (was for 50 frames) 745256 bytes.






share|improve this answer





























    up vote
    3
    down vote













    I'm sorry, really thought these should be spirals. Should have checked. Sorry! With insert path you can, of course, insert whatever you like, also a series of arcs. I have not much time now, unfortunately ...



    documentclass[tikz,border=3.14mm]standalone
    tikzsetRecaman/.style n args=3insert path=
    foreach X in #1,...,#2
    arc (-180:0:#3*(2*X-1)/2) arc (0:180:#3*2*X/2)

    begindocument
    begintikzpicture
    expandafterdraw[rounded corners] (0,1) to[out=0,in=90] (3,0)
    [Recaman=260.3] arc(-180:0:2) to[out=90,in=90] ++(3,1)
    [Recaman=270.2];
    endtikzpicture
    enddocument


    enter image description here






    share|improve this answer






















    • Thanks, I thought they were spirals as well at first, but actually they are semicircles in the visualisation I'm looking to replicate. See for example, this Numberphile video on YouTube - youtube.com/watch?time_continue=135&v=FGC5TdIiT9U
      – Milo
      Aug 25 at 11:41










    • Added some more info to my question post to describe how the sequence is formed.
      – Milo
      Aug 25 at 11:55










    • @Milo I should have definitely checked before making such a statement. Sorry!
      – marmot
      Aug 25 at 15:34










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    2 Answers
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    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    21
    down vote



    accepted










    As I am quite ignorant in TikZ I can't add the colours etc...



    • first we generate the first 1000 sequence members,


    • second, we use some kind of expandable loop in the tikz picture. For this I loaded xinttools, but there are other choices.


    • third I did three separate pictures but one can probably use in the same picture successive loops with new colors perhaps, or vary the color with index #1.


    I did not abstract into a macro with the number of steps as argument, and I did not do the work to created animated gif, but this could give a start.



    Also, I spend a bit time in TikZ manual looking for half-circles, but I got confused, so I stick with the arc construct of OP, I don't know if efficient or not for TikZ matters.



    documentclass[tikz,margin=0.5cm]standalone

    % FIRST WE GENERATE a(n) for n=0, ..., 1000
    % https://oeis.org/A005132
    makeatletter
    @namedefrecaman00@namedefnamacer00
    @namedefrecaman11@namedefnamacer11
    @namedefrecaman23@namedefnamacer32
    @namedefrecaman36@namedefnamacer63
    % <namacerN> will give the *last* index n with a(n) = N

    count@ 3
    loop
    advancecount@ @ne
    edefzzzthenumexpr
    @nameuserecamanthenumexprcount@-@ne-count@%
    @namedefrecagoleftthecount@0%
    ifnumzzz>z@
    ifcsname namacerzzzendcsname
    edefzzzthenumexprzzz+count@+count@%
    else
    @namedefrecagoleftthecount@1%
    fi
    else
    edefzzzthenumexprzzz+count@+count@%
    fi
    expandafteredefcsname recamanthecount@endcsnamezzz%
    expandafteredefcsname namacerzzzendcsnamethecount@%
    typeouta(thecount@) = @nameuserecamanthecount@%
    ifnumcount@<1000
    repeat

    usepackagexinttools

    makeatletter
    % I added the "recagoleft" in a second stage originally I was doing
    % ifnum test to check if increase or decrease for index 2*#1 and
    % 2*#1+1
    % (perhaps I should have kept more cumbersome ifnum rather than
    % creating these extra macros?)
    defmymacro#1%
    arc
    if@nameuserecagoleftthenumexpr2*#11%
    expandafter@firstoftwoelseexpandafter@secondoftwofi
    (-180:0:-thenumexpr2*#1relax)(180:0:thenumexpr2*#1relax)%
    arc
    if@nameuserecagoleftthenumexpr2*#1+11%
    expandafter@firstoftwoelseexpandafter@secondoftwofi
    (180:0:-thenumexpr2*#1+1relax)(-180:0:thenumexpr2*#1+1relax)%

    makeatother

    begindocument
    begintikzpicture
    draw [line width=3mm]
    (0,0) arc
    (-180:0:1)
    xintApplyUnbracedmymacroxintSeq110;
    endtikzpicture
    begintikzpicture
    draw [line width=3mm]
    (0,0) arc
    (-180:0:1)
    xintApplyUnbracedmymacroxintSeq130;
    endtikzpicture
    begintikzpicture
    draw [line width=3mm]
    (0,0) arc
    (-180:0:1)
    xintApplyUnbracedmymacroxintSeq150;
    endtikzpicture

    enddocument


    For generating the picture I had the problem that my usual gs invocation (with transparent background) proved very slow and produced very big png's... (13M for the third one). So I did it again with smaller resolution and here is the first one (for n=2*10=20, circa).



    enter image description here



    For the one up to n=2*50+1=101 I upload a screen capture



    enter image description here




    I realized only later that 50(i.e. n=101) was maximal with 1cm units before triggering "dimension too large error" from TikZ. But this works, where the unit is about 1.5pt (2pt would be too big).



    begintikzpicture[x=100000sp,y=100000sp]
    draw [line width=3mm]
    (0,0) arc
    (-180:0:1)
    xintApplyUnbracedmymacroxintSeq1499;% and not 500 as a(1001) not pre-computed
    endtikzpicture


    I obtain this, which indicates the values of sequence up to n=999: (sorry I initially uploaded a possibly wrong picture because I used 500, hence n=1001 but my pre-computations in preamble go only up to 1000; no error was triggered because only an if test is done about some control sequence, not a computation or an ifnum)



    enter image description here




    I am almost an expert in TikZ now: a draw statement can have only one colour. So I modified my approach to use some loop to accumulate multiple draw with a colour from an xcolor color series.



    I wanted to create an animated gif, for this reason I do a super-loop which increases the number of steps each time. My usual convert invocation failed, using seemingly the size of the first pdf page. Then I modified the code to use the same picture size for all frames. This is why in the code below I added new macros holding max(a(n), i=0..n).



    But convert again failed so I post only here a snapshot of the last frame.



    But if you compile to pdf, your PDF viewer possibly with re-create the animation for you by holding down the space key (it works for me; I configured view to a single page i.e. not "continous pages").



    documentclass[tikz]standalone
    %usepackagexcolor
    % FIRST WE GENERATE a(n) for n=0, ..., 1000
    % https://oeis.org/A005132
    makeatletter
    @namedefrecaman00@namedefnamacer00
    @namedefrecaman11@namedefnamacer11@namedefrecagoleft10
    @namedefrecaman23@namedefnamacer32@namedefrecagoleft20
    @namedefrecaman36@namedefnamacer63@namedefrecagoleft30
    % <namacerN> will give the *last* index n with a(n) = N
    @namedefrecaMax00
    @namedefrecaMax11
    @namedefrecaMax23
    @namedefrecaMax36
    count@ 3
    loop
    advancecount@ @ne
    edefzzzthenumexpr
    @nameuserecamanthenumexprcount@-@ne-count@%
    @namedefrecagoleftthecount@0%
    expandafterletcsname recaMaxthecount@expandafterendcsname
    csname recaMaxthenumexprcount@-@neendcsname
    ifnumzzz>z@
    ifcsname namacerzzzendcsname
    edefzzzthenumexprzzz+count@+count@%
    ifnumzzz>@nameuserecaMaxthecount@
    expandafterletcsname recaMaxthecount@endcsnamezzz
    fi
    else
    @namedefrecagoleftthecount@1%
    fi
    else
    edefzzzthenumexprzzz+count@+count@%
    ifnumzzz>@nameuserecaMaxthecount@
    expandafterletcsname recaMaxthecount@endcsnamezzz
    fi
    fi
    expandafterletcsname recamanthecount@endcsnamezzz
    expandafteredefcsname namacerzzzendcsnamethecount@%
    typeouta(thecount@) = @nameuserecamanthecount@
    (max so far=@nameuserecaMaxthecount@)%
    ifnumcount@<1000
    repeat

    usepackagexinttools

    makeatletter
    defmymacro#1%
    draw
    [color=foo!!+]
    % radius being n, width of circle 2n, end-point is at 2*a(n)
    (2*@nameuserecamanthenumexpr#1-1,0)
    arc
    if@nameuserecagoleft#11%
    expandafter@firstoftwoelseexpandafter@secondoftwofi
    (unlessifodd#1 -fi180:0:-#1)(ifodd#1 -fi180:0:#1);%

    makeatother

    makeatletter
    defdrawframe#1noexpand
    draw
    (0,0)--(0,-#1)--(thenumexpr2*@nameuserecaMax#1,-#1)
    --(thenumexpr2*@nameuserecaMax#1,#1)--(0,#1)--cycle;%
    makeatother

    definecolorseriesfoorgblastbluered

    begindocument

    xintFor* #1 in xintSeq1100do%
    begintikzpicture[x=5mm, y=5mm]
    edefzzzdrawframe100zzz% get all pictures to be of same size
    resetcolorseries[#1]foo%
    xintApplyUnbracedmymacroxintSeq1#1
    endtikzpicture


    enddocument


    Here is thus page 100 of the produced PDF:



    enter image description here




    I finally manage to get an animated gif:



    enter image description here
    Recipe:



    • 65 frames,


    • [x=1mm, y=1mm],

    • each draw with line width=.5mm,

    • pdflatex

    • convert -density 72 recaman-colors.pdf _tmp%02d.png

    • convert -verbose -dispose previous -loop 0 -density 100 -delay 15 _tmp00..9.png _tmp10..63.png -delay 300 _tmp64.png recaman.gif

    Output not as smooth as one could hope, but 360383 (was for 50 frames) 745256 bytes.






    share|improve this answer


























      up vote
      21
      down vote



      accepted










      As I am quite ignorant in TikZ I can't add the colours etc...



      • first we generate the first 1000 sequence members,


      • second, we use some kind of expandable loop in the tikz picture. For this I loaded xinttools, but there are other choices.


      • third I did three separate pictures but one can probably use in the same picture successive loops with new colors perhaps, or vary the color with index #1.


      I did not abstract into a macro with the number of steps as argument, and I did not do the work to created animated gif, but this could give a start.



      Also, I spend a bit time in TikZ manual looking for half-circles, but I got confused, so I stick with the arc construct of OP, I don't know if efficient or not for TikZ matters.



      documentclass[tikz,margin=0.5cm]standalone

      % FIRST WE GENERATE a(n) for n=0, ..., 1000
      % https://oeis.org/A005132
      makeatletter
      @namedefrecaman00@namedefnamacer00
      @namedefrecaman11@namedefnamacer11
      @namedefrecaman23@namedefnamacer32
      @namedefrecaman36@namedefnamacer63
      % <namacerN> will give the *last* index n with a(n) = N

      count@ 3
      loop
      advancecount@ @ne
      edefzzzthenumexpr
      @nameuserecamanthenumexprcount@-@ne-count@%
      @namedefrecagoleftthecount@0%
      ifnumzzz>z@
      ifcsname namacerzzzendcsname
      edefzzzthenumexprzzz+count@+count@%
      else
      @namedefrecagoleftthecount@1%
      fi
      else
      edefzzzthenumexprzzz+count@+count@%
      fi
      expandafteredefcsname recamanthecount@endcsnamezzz%
      expandafteredefcsname namacerzzzendcsnamethecount@%
      typeouta(thecount@) = @nameuserecamanthecount@%
      ifnumcount@<1000
      repeat

      usepackagexinttools

      makeatletter
      % I added the "recagoleft" in a second stage originally I was doing
      % ifnum test to check if increase or decrease for index 2*#1 and
      % 2*#1+1
      % (perhaps I should have kept more cumbersome ifnum rather than
      % creating these extra macros?)
      defmymacro#1%
      arc
      if@nameuserecagoleftthenumexpr2*#11%
      expandafter@firstoftwoelseexpandafter@secondoftwofi
      (-180:0:-thenumexpr2*#1relax)(180:0:thenumexpr2*#1relax)%
      arc
      if@nameuserecagoleftthenumexpr2*#1+11%
      expandafter@firstoftwoelseexpandafter@secondoftwofi
      (180:0:-thenumexpr2*#1+1relax)(-180:0:thenumexpr2*#1+1relax)%

      makeatother

      begindocument
      begintikzpicture
      draw [line width=3mm]
      (0,0) arc
      (-180:0:1)
      xintApplyUnbracedmymacroxintSeq110;
      endtikzpicture
      begintikzpicture
      draw [line width=3mm]
      (0,0) arc
      (-180:0:1)
      xintApplyUnbracedmymacroxintSeq130;
      endtikzpicture
      begintikzpicture
      draw [line width=3mm]
      (0,0) arc
      (-180:0:1)
      xintApplyUnbracedmymacroxintSeq150;
      endtikzpicture

      enddocument


      For generating the picture I had the problem that my usual gs invocation (with transparent background) proved very slow and produced very big png's... (13M for the third one). So I did it again with smaller resolution and here is the first one (for n=2*10=20, circa).



      enter image description here



      For the one up to n=2*50+1=101 I upload a screen capture



      enter image description here




      I realized only later that 50(i.e. n=101) was maximal with 1cm units before triggering "dimension too large error" from TikZ. But this works, where the unit is about 1.5pt (2pt would be too big).



      begintikzpicture[x=100000sp,y=100000sp]
      draw [line width=3mm]
      (0,0) arc
      (-180:0:1)
      xintApplyUnbracedmymacroxintSeq1499;% and not 500 as a(1001) not pre-computed
      endtikzpicture


      I obtain this, which indicates the values of sequence up to n=999: (sorry I initially uploaded a possibly wrong picture because I used 500, hence n=1001 but my pre-computations in preamble go only up to 1000; no error was triggered because only an if test is done about some control sequence, not a computation or an ifnum)



      enter image description here




      I am almost an expert in TikZ now: a draw statement can have only one colour. So I modified my approach to use some loop to accumulate multiple draw with a colour from an xcolor color series.



      I wanted to create an animated gif, for this reason I do a super-loop which increases the number of steps each time. My usual convert invocation failed, using seemingly the size of the first pdf page. Then I modified the code to use the same picture size for all frames. This is why in the code below I added new macros holding max(a(n), i=0..n).



      But convert again failed so I post only here a snapshot of the last frame.



      But if you compile to pdf, your PDF viewer possibly with re-create the animation for you by holding down the space key (it works for me; I configured view to a single page i.e. not "continous pages").



      documentclass[tikz]standalone
      %usepackagexcolor
      % FIRST WE GENERATE a(n) for n=0, ..., 1000
      % https://oeis.org/A005132
      makeatletter
      @namedefrecaman00@namedefnamacer00
      @namedefrecaman11@namedefnamacer11@namedefrecagoleft10
      @namedefrecaman23@namedefnamacer32@namedefrecagoleft20
      @namedefrecaman36@namedefnamacer63@namedefrecagoleft30
      % <namacerN> will give the *last* index n with a(n) = N
      @namedefrecaMax00
      @namedefrecaMax11
      @namedefrecaMax23
      @namedefrecaMax36
      count@ 3
      loop
      advancecount@ @ne
      edefzzzthenumexpr
      @nameuserecamanthenumexprcount@-@ne-count@%
      @namedefrecagoleftthecount@0%
      expandafterletcsname recaMaxthecount@expandafterendcsname
      csname recaMaxthenumexprcount@-@neendcsname
      ifnumzzz>z@
      ifcsname namacerzzzendcsname
      edefzzzthenumexprzzz+count@+count@%
      ifnumzzz>@nameuserecaMaxthecount@
      expandafterletcsname recaMaxthecount@endcsnamezzz
      fi
      else
      @namedefrecagoleftthecount@1%
      fi
      else
      edefzzzthenumexprzzz+count@+count@%
      ifnumzzz>@nameuserecaMaxthecount@
      expandafterletcsname recaMaxthecount@endcsnamezzz
      fi
      fi
      expandafterletcsname recamanthecount@endcsnamezzz
      expandafteredefcsname namacerzzzendcsnamethecount@%
      typeouta(thecount@) = @nameuserecamanthecount@
      (max so far=@nameuserecaMaxthecount@)%
      ifnumcount@<1000
      repeat

      usepackagexinttools

      makeatletter
      defmymacro#1%
      draw
      [color=foo!!+]
      % radius being n, width of circle 2n, end-point is at 2*a(n)
      (2*@nameuserecamanthenumexpr#1-1,0)
      arc
      if@nameuserecagoleft#11%
      expandafter@firstoftwoelseexpandafter@secondoftwofi
      (unlessifodd#1 -fi180:0:-#1)(ifodd#1 -fi180:0:#1);%

      makeatother

      makeatletter
      defdrawframe#1noexpand
      draw
      (0,0)--(0,-#1)--(thenumexpr2*@nameuserecaMax#1,-#1)
      --(thenumexpr2*@nameuserecaMax#1,#1)--(0,#1)--cycle;%
      makeatother

      definecolorseriesfoorgblastbluered

      begindocument

      xintFor* #1 in xintSeq1100do%
      begintikzpicture[x=5mm, y=5mm]
      edefzzzdrawframe100zzz% get all pictures to be of same size
      resetcolorseries[#1]foo%
      xintApplyUnbracedmymacroxintSeq1#1
      endtikzpicture


      enddocument


      Here is thus page 100 of the produced PDF:



      enter image description here




      I finally manage to get an animated gif:



      enter image description here
      Recipe:



      • 65 frames,


      • [x=1mm, y=1mm],

      • each draw with line width=.5mm,

      • pdflatex

      • convert -density 72 recaman-colors.pdf _tmp%02d.png

      • convert -verbose -dispose previous -loop 0 -density 100 -delay 15 _tmp00..9.png _tmp10..63.png -delay 300 _tmp64.png recaman.gif

      Output not as smooth as one could hope, but 360383 (was for 50 frames) 745256 bytes.






      share|improve this answer
























        up vote
        21
        down vote



        accepted







        up vote
        21
        down vote



        accepted






        As I am quite ignorant in TikZ I can't add the colours etc...



        • first we generate the first 1000 sequence members,


        • second, we use some kind of expandable loop in the tikz picture. For this I loaded xinttools, but there are other choices.


        • third I did three separate pictures but one can probably use in the same picture successive loops with new colors perhaps, or vary the color with index #1.


        I did not abstract into a macro with the number of steps as argument, and I did not do the work to created animated gif, but this could give a start.



        Also, I spend a bit time in TikZ manual looking for half-circles, but I got confused, so I stick with the arc construct of OP, I don't know if efficient or not for TikZ matters.



        documentclass[tikz,margin=0.5cm]standalone

        % FIRST WE GENERATE a(n) for n=0, ..., 1000
        % https://oeis.org/A005132
        makeatletter
        @namedefrecaman00@namedefnamacer00
        @namedefrecaman11@namedefnamacer11
        @namedefrecaman23@namedefnamacer32
        @namedefrecaman36@namedefnamacer63
        % <namacerN> will give the *last* index n with a(n) = N

        count@ 3
        loop
        advancecount@ @ne
        edefzzzthenumexpr
        @nameuserecamanthenumexprcount@-@ne-count@%
        @namedefrecagoleftthecount@0%
        ifnumzzz>z@
        ifcsname namacerzzzendcsname
        edefzzzthenumexprzzz+count@+count@%
        else
        @namedefrecagoleftthecount@1%
        fi
        else
        edefzzzthenumexprzzz+count@+count@%
        fi
        expandafteredefcsname recamanthecount@endcsnamezzz%
        expandafteredefcsname namacerzzzendcsnamethecount@%
        typeouta(thecount@) = @nameuserecamanthecount@%
        ifnumcount@<1000
        repeat

        usepackagexinttools

        makeatletter
        % I added the "recagoleft" in a second stage originally I was doing
        % ifnum test to check if increase or decrease for index 2*#1 and
        % 2*#1+1
        % (perhaps I should have kept more cumbersome ifnum rather than
        % creating these extra macros?)
        defmymacro#1%
        arc
        if@nameuserecagoleftthenumexpr2*#11%
        expandafter@firstoftwoelseexpandafter@secondoftwofi
        (-180:0:-thenumexpr2*#1relax)(180:0:thenumexpr2*#1relax)%
        arc
        if@nameuserecagoleftthenumexpr2*#1+11%
        expandafter@firstoftwoelseexpandafter@secondoftwofi
        (180:0:-thenumexpr2*#1+1relax)(-180:0:thenumexpr2*#1+1relax)%

        makeatother

        begindocument
        begintikzpicture
        draw [line width=3mm]
        (0,0) arc
        (-180:0:1)
        xintApplyUnbracedmymacroxintSeq110;
        endtikzpicture
        begintikzpicture
        draw [line width=3mm]
        (0,0) arc
        (-180:0:1)
        xintApplyUnbracedmymacroxintSeq130;
        endtikzpicture
        begintikzpicture
        draw [line width=3mm]
        (0,0) arc
        (-180:0:1)
        xintApplyUnbracedmymacroxintSeq150;
        endtikzpicture

        enddocument


        For generating the picture I had the problem that my usual gs invocation (with transparent background) proved very slow and produced very big png's... (13M for the third one). So I did it again with smaller resolution and here is the first one (for n=2*10=20, circa).



        enter image description here



        For the one up to n=2*50+1=101 I upload a screen capture



        enter image description here




        I realized only later that 50(i.e. n=101) was maximal with 1cm units before triggering "dimension too large error" from TikZ. But this works, where the unit is about 1.5pt (2pt would be too big).



        begintikzpicture[x=100000sp,y=100000sp]
        draw [line width=3mm]
        (0,0) arc
        (-180:0:1)
        xintApplyUnbracedmymacroxintSeq1499;% and not 500 as a(1001) not pre-computed
        endtikzpicture


        I obtain this, which indicates the values of sequence up to n=999: (sorry I initially uploaded a possibly wrong picture because I used 500, hence n=1001 but my pre-computations in preamble go only up to 1000; no error was triggered because only an if test is done about some control sequence, not a computation or an ifnum)



        enter image description here




        I am almost an expert in TikZ now: a draw statement can have only one colour. So I modified my approach to use some loop to accumulate multiple draw with a colour from an xcolor color series.



        I wanted to create an animated gif, for this reason I do a super-loop which increases the number of steps each time. My usual convert invocation failed, using seemingly the size of the first pdf page. Then I modified the code to use the same picture size for all frames. This is why in the code below I added new macros holding max(a(n), i=0..n).



        But convert again failed so I post only here a snapshot of the last frame.



        But if you compile to pdf, your PDF viewer possibly with re-create the animation for you by holding down the space key (it works for me; I configured view to a single page i.e. not "continous pages").



        documentclass[tikz]standalone
        %usepackagexcolor
        % FIRST WE GENERATE a(n) for n=0, ..., 1000
        % https://oeis.org/A005132
        makeatletter
        @namedefrecaman00@namedefnamacer00
        @namedefrecaman11@namedefnamacer11@namedefrecagoleft10
        @namedefrecaman23@namedefnamacer32@namedefrecagoleft20
        @namedefrecaman36@namedefnamacer63@namedefrecagoleft30
        % <namacerN> will give the *last* index n with a(n) = N
        @namedefrecaMax00
        @namedefrecaMax11
        @namedefrecaMax23
        @namedefrecaMax36
        count@ 3
        loop
        advancecount@ @ne
        edefzzzthenumexpr
        @nameuserecamanthenumexprcount@-@ne-count@%
        @namedefrecagoleftthecount@0%
        expandafterletcsname recaMaxthecount@expandafterendcsname
        csname recaMaxthenumexprcount@-@neendcsname
        ifnumzzz>z@
        ifcsname namacerzzzendcsname
        edefzzzthenumexprzzz+count@+count@%
        ifnumzzz>@nameuserecaMaxthecount@
        expandafterletcsname recaMaxthecount@endcsnamezzz
        fi
        else
        @namedefrecagoleftthecount@1%
        fi
        else
        edefzzzthenumexprzzz+count@+count@%
        ifnumzzz>@nameuserecaMaxthecount@
        expandafterletcsname recaMaxthecount@endcsnamezzz
        fi
        fi
        expandafterletcsname recamanthecount@endcsnamezzz
        expandafteredefcsname namacerzzzendcsnamethecount@%
        typeouta(thecount@) = @nameuserecamanthecount@
        (max so far=@nameuserecaMaxthecount@)%
        ifnumcount@<1000
        repeat

        usepackagexinttools

        makeatletter
        defmymacro#1%
        draw
        [color=foo!!+]
        % radius being n, width of circle 2n, end-point is at 2*a(n)
        (2*@nameuserecamanthenumexpr#1-1,0)
        arc
        if@nameuserecagoleft#11%
        expandafter@firstoftwoelseexpandafter@secondoftwofi
        (unlessifodd#1 -fi180:0:-#1)(ifodd#1 -fi180:0:#1);%

        makeatother

        makeatletter
        defdrawframe#1noexpand
        draw
        (0,0)--(0,-#1)--(thenumexpr2*@nameuserecaMax#1,-#1)
        --(thenumexpr2*@nameuserecaMax#1,#1)--(0,#1)--cycle;%
        makeatother

        definecolorseriesfoorgblastbluered

        begindocument

        xintFor* #1 in xintSeq1100do%
        begintikzpicture[x=5mm, y=5mm]
        edefzzzdrawframe100zzz% get all pictures to be of same size
        resetcolorseries[#1]foo%
        xintApplyUnbracedmymacroxintSeq1#1
        endtikzpicture


        enddocument


        Here is thus page 100 of the produced PDF:



        enter image description here




        I finally manage to get an animated gif:



        enter image description here
        Recipe:



        • 65 frames,


        • [x=1mm, y=1mm],

        • each draw with line width=.5mm,

        • pdflatex

        • convert -density 72 recaman-colors.pdf _tmp%02d.png

        • convert -verbose -dispose previous -loop 0 -density 100 -delay 15 _tmp00..9.png _tmp10..63.png -delay 300 _tmp64.png recaman.gif

        Output not as smooth as one could hope, but 360383 (was for 50 frames) 745256 bytes.






        share|improve this answer














        As I am quite ignorant in TikZ I can't add the colours etc...



        • first we generate the first 1000 sequence members,


        • second, we use some kind of expandable loop in the tikz picture. For this I loaded xinttools, but there are other choices.


        • third I did three separate pictures but one can probably use in the same picture successive loops with new colors perhaps, or vary the color with index #1.


        I did not abstract into a macro with the number of steps as argument, and I did not do the work to created animated gif, but this could give a start.



        Also, I spend a bit time in TikZ manual looking for half-circles, but I got confused, so I stick with the arc construct of OP, I don't know if efficient or not for TikZ matters.



        documentclass[tikz,margin=0.5cm]standalone

        % FIRST WE GENERATE a(n) for n=0, ..., 1000
        % https://oeis.org/A005132
        makeatletter
        @namedefrecaman00@namedefnamacer00
        @namedefrecaman11@namedefnamacer11
        @namedefrecaman23@namedefnamacer32
        @namedefrecaman36@namedefnamacer63
        % <namacerN> will give the *last* index n with a(n) = N

        count@ 3
        loop
        advancecount@ @ne
        edefzzzthenumexpr
        @nameuserecamanthenumexprcount@-@ne-count@%
        @namedefrecagoleftthecount@0%
        ifnumzzz>z@
        ifcsname namacerzzzendcsname
        edefzzzthenumexprzzz+count@+count@%
        else
        @namedefrecagoleftthecount@1%
        fi
        else
        edefzzzthenumexprzzz+count@+count@%
        fi
        expandafteredefcsname recamanthecount@endcsnamezzz%
        expandafteredefcsname namacerzzzendcsnamethecount@%
        typeouta(thecount@) = @nameuserecamanthecount@%
        ifnumcount@<1000
        repeat

        usepackagexinttools

        makeatletter
        % I added the "recagoleft" in a second stage originally I was doing
        % ifnum test to check if increase or decrease for index 2*#1 and
        % 2*#1+1
        % (perhaps I should have kept more cumbersome ifnum rather than
        % creating these extra macros?)
        defmymacro#1%
        arc
        if@nameuserecagoleftthenumexpr2*#11%
        expandafter@firstoftwoelseexpandafter@secondoftwofi
        (-180:0:-thenumexpr2*#1relax)(180:0:thenumexpr2*#1relax)%
        arc
        if@nameuserecagoleftthenumexpr2*#1+11%
        expandafter@firstoftwoelseexpandafter@secondoftwofi
        (180:0:-thenumexpr2*#1+1relax)(-180:0:thenumexpr2*#1+1relax)%

        makeatother

        begindocument
        begintikzpicture
        draw [line width=3mm]
        (0,0) arc
        (-180:0:1)
        xintApplyUnbracedmymacroxintSeq110;
        endtikzpicture
        begintikzpicture
        draw [line width=3mm]
        (0,0) arc
        (-180:0:1)
        xintApplyUnbracedmymacroxintSeq130;
        endtikzpicture
        begintikzpicture
        draw [line width=3mm]
        (0,0) arc
        (-180:0:1)
        xintApplyUnbracedmymacroxintSeq150;
        endtikzpicture

        enddocument


        For generating the picture I had the problem that my usual gs invocation (with transparent background) proved very slow and produced very big png's... (13M for the third one). So I did it again with smaller resolution and here is the first one (for n=2*10=20, circa).



        enter image description here



        For the one up to n=2*50+1=101 I upload a screen capture



        enter image description here




        I realized only later that 50(i.e. n=101) was maximal with 1cm units before triggering "dimension too large error" from TikZ. But this works, where the unit is about 1.5pt (2pt would be too big).



        begintikzpicture[x=100000sp,y=100000sp]
        draw [line width=3mm]
        (0,0) arc
        (-180:0:1)
        xintApplyUnbracedmymacroxintSeq1499;% and not 500 as a(1001) not pre-computed
        endtikzpicture


        I obtain this, which indicates the values of sequence up to n=999: (sorry I initially uploaded a possibly wrong picture because I used 500, hence n=1001 but my pre-computations in preamble go only up to 1000; no error was triggered because only an if test is done about some control sequence, not a computation or an ifnum)



        enter image description here




        I am almost an expert in TikZ now: a draw statement can have only one colour. So I modified my approach to use some loop to accumulate multiple draw with a colour from an xcolor color series.



        I wanted to create an animated gif, for this reason I do a super-loop which increases the number of steps each time. My usual convert invocation failed, using seemingly the size of the first pdf page. Then I modified the code to use the same picture size for all frames. This is why in the code below I added new macros holding max(a(n), i=0..n).



        But convert again failed so I post only here a snapshot of the last frame.



        But if you compile to pdf, your PDF viewer possibly with re-create the animation for you by holding down the space key (it works for me; I configured view to a single page i.e. not "continous pages").



        documentclass[tikz]standalone
        %usepackagexcolor
        % FIRST WE GENERATE a(n) for n=0, ..., 1000
        % https://oeis.org/A005132
        makeatletter
        @namedefrecaman00@namedefnamacer00
        @namedefrecaman11@namedefnamacer11@namedefrecagoleft10
        @namedefrecaman23@namedefnamacer32@namedefrecagoleft20
        @namedefrecaman36@namedefnamacer63@namedefrecagoleft30
        % <namacerN> will give the *last* index n with a(n) = N
        @namedefrecaMax00
        @namedefrecaMax11
        @namedefrecaMax23
        @namedefrecaMax36
        count@ 3
        loop
        advancecount@ @ne
        edefzzzthenumexpr
        @nameuserecamanthenumexprcount@-@ne-count@%
        @namedefrecagoleftthecount@0%
        expandafterletcsname recaMaxthecount@expandafterendcsname
        csname recaMaxthenumexprcount@-@neendcsname
        ifnumzzz>z@
        ifcsname namacerzzzendcsname
        edefzzzthenumexprzzz+count@+count@%
        ifnumzzz>@nameuserecaMaxthecount@
        expandafterletcsname recaMaxthecount@endcsnamezzz
        fi
        else
        @namedefrecagoleftthecount@1%
        fi
        else
        edefzzzthenumexprzzz+count@+count@%
        ifnumzzz>@nameuserecaMaxthecount@
        expandafterletcsname recaMaxthecount@endcsnamezzz
        fi
        fi
        expandafterletcsname recamanthecount@endcsnamezzz
        expandafteredefcsname namacerzzzendcsnamethecount@%
        typeouta(thecount@) = @nameuserecamanthecount@
        (max so far=@nameuserecaMaxthecount@)%
        ifnumcount@<1000
        repeat

        usepackagexinttools

        makeatletter
        defmymacro#1%
        draw
        [color=foo!!+]
        % radius being n, width of circle 2n, end-point is at 2*a(n)
        (2*@nameuserecamanthenumexpr#1-1,0)
        arc
        if@nameuserecagoleft#11%
        expandafter@firstoftwoelseexpandafter@secondoftwofi
        (unlessifodd#1 -fi180:0:-#1)(ifodd#1 -fi180:0:#1);%

        makeatother

        makeatletter
        defdrawframe#1noexpand
        draw
        (0,0)--(0,-#1)--(thenumexpr2*@nameuserecaMax#1,-#1)
        --(thenumexpr2*@nameuserecaMax#1,#1)--(0,#1)--cycle;%
        makeatother

        definecolorseriesfoorgblastbluered

        begindocument

        xintFor* #1 in xintSeq1100do%
        begintikzpicture[x=5mm, y=5mm]
        edefzzzdrawframe100zzz% get all pictures to be of same size
        resetcolorseries[#1]foo%
        xintApplyUnbracedmymacroxintSeq1#1
        endtikzpicture


        enddocument


        Here is thus page 100 of the produced PDF:



        enter image description here




        I finally manage to get an animated gif:



        enter image description here
        Recipe:



        • 65 frames,


        • [x=1mm, y=1mm],

        • each draw with line width=.5mm,

        • pdflatex

        • convert -density 72 recaman-colors.pdf _tmp%02d.png

        • convert -verbose -dispose previous -loop 0 -density 100 -delay 15 _tmp00..9.png _tmp10..63.png -delay 300 _tmp64.png recaman.gif

        Output not as smooth as one could hope, but 360383 (was for 50 frames) 745256 bytes.







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Aug 28 at 22:00

























        answered Aug 25 at 14:16









        jfbu

        41.6k60131




        41.6k60131




















            up vote
            3
            down vote













            I'm sorry, really thought these should be spirals. Should have checked. Sorry! With insert path you can, of course, insert whatever you like, also a series of arcs. I have not much time now, unfortunately ...



            documentclass[tikz,border=3.14mm]standalone
            tikzsetRecaman/.style n args=3insert path=
            foreach X in #1,...,#2
            arc (-180:0:#3*(2*X-1)/2) arc (0:180:#3*2*X/2)

            begindocument
            begintikzpicture
            expandafterdraw[rounded corners] (0,1) to[out=0,in=90] (3,0)
            [Recaman=260.3] arc(-180:0:2) to[out=90,in=90] ++(3,1)
            [Recaman=270.2];
            endtikzpicture
            enddocument


            enter image description here






            share|improve this answer






















            • Thanks, I thought they were spirals as well at first, but actually they are semicircles in the visualisation I'm looking to replicate. See for example, this Numberphile video on YouTube - youtube.com/watch?time_continue=135&v=FGC5TdIiT9U
              – Milo
              Aug 25 at 11:41










            • Added some more info to my question post to describe how the sequence is formed.
              – Milo
              Aug 25 at 11:55










            • @Milo I should have definitely checked before making such a statement. Sorry!
              – marmot
              Aug 25 at 15:34














            up vote
            3
            down vote













            I'm sorry, really thought these should be spirals. Should have checked. Sorry! With insert path you can, of course, insert whatever you like, also a series of arcs. I have not much time now, unfortunately ...



            documentclass[tikz,border=3.14mm]standalone
            tikzsetRecaman/.style n args=3insert path=
            foreach X in #1,...,#2
            arc (-180:0:#3*(2*X-1)/2) arc (0:180:#3*2*X/2)

            begindocument
            begintikzpicture
            expandafterdraw[rounded corners] (0,1) to[out=0,in=90] (3,0)
            [Recaman=260.3] arc(-180:0:2) to[out=90,in=90] ++(3,1)
            [Recaman=270.2];
            endtikzpicture
            enddocument


            enter image description here






            share|improve this answer






















            • Thanks, I thought they were spirals as well at first, but actually they are semicircles in the visualisation I'm looking to replicate. See for example, this Numberphile video on YouTube - youtube.com/watch?time_continue=135&v=FGC5TdIiT9U
              – Milo
              Aug 25 at 11:41










            • Added some more info to my question post to describe how the sequence is formed.
              – Milo
              Aug 25 at 11:55










            • @Milo I should have definitely checked before making such a statement. Sorry!
              – marmot
              Aug 25 at 15:34












            up vote
            3
            down vote










            up vote
            3
            down vote









            I'm sorry, really thought these should be spirals. Should have checked. Sorry! With insert path you can, of course, insert whatever you like, also a series of arcs. I have not much time now, unfortunately ...



            documentclass[tikz,border=3.14mm]standalone
            tikzsetRecaman/.style n args=3insert path=
            foreach X in #1,...,#2
            arc (-180:0:#3*(2*X-1)/2) arc (0:180:#3*2*X/2)

            begindocument
            begintikzpicture
            expandafterdraw[rounded corners] (0,1) to[out=0,in=90] (3,0)
            [Recaman=260.3] arc(-180:0:2) to[out=90,in=90] ++(3,1)
            [Recaman=270.2];
            endtikzpicture
            enddocument


            enter image description here






            share|improve this answer














            I'm sorry, really thought these should be spirals. Should have checked. Sorry! With insert path you can, of course, insert whatever you like, also a series of arcs. I have not much time now, unfortunately ...



            documentclass[tikz,border=3.14mm]standalone
            tikzsetRecaman/.style n args=3insert path=
            foreach X in #1,...,#2
            arc (-180:0:#3*(2*X-1)/2) arc (0:180:#3*2*X/2)

            begindocument
            begintikzpicture
            expandafterdraw[rounded corners] (0,1) to[out=0,in=90] (3,0)
            [Recaman=260.3] arc(-180:0:2) to[out=90,in=90] ++(3,1)
            [Recaman=270.2];
            endtikzpicture
            enddocument


            enter image description here







            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited Aug 25 at 15:32

























            answered Aug 25 at 11:26









            marmot

            55.6k461121




            55.6k461121











            • Thanks, I thought they were spirals as well at first, but actually they are semicircles in the visualisation I'm looking to replicate. See for example, this Numberphile video on YouTube - youtube.com/watch?time_continue=135&v=FGC5TdIiT9U
              – Milo
              Aug 25 at 11:41










            • Added some more info to my question post to describe how the sequence is formed.
              – Milo
              Aug 25 at 11:55










            • @Milo I should have definitely checked before making such a statement. Sorry!
              – marmot
              Aug 25 at 15:34
















            • Thanks, I thought they were spirals as well at first, but actually they are semicircles in the visualisation I'm looking to replicate. See for example, this Numberphile video on YouTube - youtube.com/watch?time_continue=135&v=FGC5TdIiT9U
              – Milo
              Aug 25 at 11:41










            • Added some more info to my question post to describe how the sequence is formed.
              – Milo
              Aug 25 at 11:55










            • @Milo I should have definitely checked before making such a statement. Sorry!
              – marmot
              Aug 25 at 15:34















            Thanks, I thought they were spirals as well at first, but actually they are semicircles in the visualisation I'm looking to replicate. See for example, this Numberphile video on YouTube - youtube.com/watch?time_continue=135&v=FGC5TdIiT9U
            – Milo
            Aug 25 at 11:41




            Thanks, I thought they were spirals as well at first, but actually they are semicircles in the visualisation I'm looking to replicate. See for example, this Numberphile video on YouTube - youtube.com/watch?time_continue=135&v=FGC5TdIiT9U
            – Milo
            Aug 25 at 11:41












            Added some more info to my question post to describe how the sequence is formed.
            – Milo
            Aug 25 at 11:55




            Added some more info to my question post to describe how the sequence is formed.
            – Milo
            Aug 25 at 11:55












            @Milo I should have definitely checked before making such a statement. Sorry!
            – marmot
            Aug 25 at 15:34




            @Milo I should have definitely checked before making such a statement. Sorry!
            – marmot
            Aug 25 at 15:34

















             

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