31:T7ee,md`Also, because I just had the enjoyment of writing PostScript for the very first time... If you save the below as recaman.eps, and then run ps2pdf recaman.eps on it, you get a nice pdf file with the same stuff :D Primary resource: http://www.cburch.com/csbsju/cs/portfolio/postscript.pdf. Also, don't kill yourself over the unpleasant interactivity of the gs command, while just trying to get to the bottom of this low-level stack-based language—use rlwrap gs -sDEVICE=bbox instead.

%!PS-Adobe-3.0 EPSF-3.0
%%BoundingBox: 0 0 595 842

% for coding: rlwrap gs -sDEVICE=bbox

/pagewidth  currentpagedevice /PageSize get 0 get def
/pageheight currentpagedevice /PageSize get 1 get def

/u {2 mul} def
.5 setlinewidth

/N 200 def

/upperbound 0 def
0 1 N {
  upperbound add /upperbound exch def
} for

/had upperbound array def
/seq upperbound array def

seq 0 0 put
had 0 true put
1 1 had length 1 sub {
  had exch false put
} for

/max {
  /x exch def
  /y exch def
  x y le { y } { x } ifelse
} def

/abs {
  /x exch def
  x 0 lt { 0 x sub } { x } ifelse
} def

/mid {
  /x exch def
  /y exch def
  x y add 2 div
} def

/pa {
  /arr exch def
  0 1 arr length 1 sub {
    arr exch get =
  } for
} def

0 1 N {
  /i exch def
  /n seq i get def
  /m n i sub 1 sub def
  m 0 lt had m 0 max get or {
    /m n i add 1 add def
  } if
  had m true put
  seq i 1 add m put
} for

/cy pageheight 2 div def
0 1 N 1 sub {
  /i exch def
  /n seq i get def
  /m seq i 1 add get def
  /r n u m u sub abs 2 div def
  /cx n u m u mid def
  /s i 2 mod 180 mul def
  cx cy r 0 s add 180 s sub arc stroke
} for

showpage
%%EOF

`32:[] 2f:{"title":"The Recamán sequence","cells":[{"id":0,"value":"md`# The Recamán sequence`","pinned":false,"hidden":false,"mode":"ojs"},{"id":260,"value":"md`See also:\n\n- The Slightly Spooky Recamán Sequence - Numberphile ([YouTube video](https://www.youtube.com/watch?v=FGC5TdIiT9U))\n- The On-Line Encyclopedia of Integer Sequences ([entry #A005132](https://oeis.org/A005132))\n\n*Note: The sliders below are restricted to reasonable maximums, but just for aesthetic reasons. Feel free to bump the numbers!* :D`","pinned":false,"hidden":false,"mode":"ojs"},{"id":8,"value":"html``","pinned":false,"hidden":false,"mode":"ojs"},{"id":128,"value":"viewof len = slider({ min: 1, max: 500, step: 1, value: 200 })","pinned":false,"hidden":false,"mode":"ojs"},{"id":241,"value":"viewof zoomout = slider({ min: 1, max: 10, value: 2.7 })","pinned":false,"hidden":false,"mode":"ojs"},{"id":20,"value":"md`${list.join(', ')}…`","pinned":false,"hidden":false,"mode":"ojs"},{"id":310,"value":"md`## Bonus material: PostScript implementation`","pinned":false,"hidden":false,"mode":"ojs"},{"id":293,"value":"$31","pinned":false,"hidden":false,"mode":"ojs"},{"id":291,"value":"md`## Implementation stuff`","pinned":false,"hidden":false,"mode":"ojs"},{"id":257,"value":"arcdata = {\n var d = 'M0 0';\n var max = 0;\n \n list.reduce((n0, n1, i) => {\n const w = Math.abs(n1 - n0);\n const s = (i + (n1-n0 > 0 ? 1 : 0)) % 2;\n d += `A 1 1 0 0 ${s} ${n1*10} 0`;\n return n1;\n });\n \n return { d, max };\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":139,"value":"list = seq(len)","pinned":false,"hidden":false,"mode":"ojs"},{"id":14,"value":"function seq (len) {\n \n while (cache.seq.length < len) {\n const k = cache.seq.length;\n const n = cache.seq[k-1];\n if (n-k < 0 || cache.had[n-k]) {\n cache.had[n+k] = true;\n cache.seq.push(n+k);\n } else {\n cache.had[n-k] = true;\n cache.seq.push(n-k);\n }\n }\n \n return cache.seq.slice(0, len);\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":44,"value":"viewof cache = {\n const view = md`**[Cache object]**`;\n view.value = { seq: [0], had: [true] };\n return view;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":124,"value":"import { slider } from '@jashkenas/inputs'","pinned":false,"hidden":false,"mode":"ojs"}],"files":"$W32","stdlib":"1","titling":"auto"}