This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A233136 #4 Dec 07 2013 12:56:30
%S A233136 1,2,2,1,2,2,2,2,1,2,1,2,2,1,2,1,2,2,2,2,2,2,1,2,2,1,2,2,2,1,2,1,2,1,
%T A233136 2,2,2,1,2,2,1,2,1,2,1,2,2,1,2,1,2,1,2,2,2,2,2,2,2,2,1,2,2,2,1,2,2,2,
%U A233136 2,1,2,1,2,2,1,2,2,2,2,1,2,2,1,2,2,1
%N A233136 Concatenated shortest (x+1,2x)-codes for the positive integers.
%C A233136 Concatenate the representations of the positive integers in A233135, and then separate the digits by commas, in the manner analogous to A030302.
%H A233136 Clark Kimberling, <a href="/A233136/b233136.txt">Table of n, a(n) for n = 1..2500</a>
%e A233136 A233135 = (1,2,21,22,221,212,...), so that A233136 = (1,2,2,1,2,2,2,2,1,2,1,2,...).
%t A233136 b[x_] := b[x] = If[OddQ[x], x - 1, x/2]; u[n_] := 2 - Mod[Drop[FixedPointList[b, n], -3], 2]; u[1] = {1}; t = Table[u[n], {n, 1, 30}]; Table[FromDigits[u[n]], {n, 1, 50}] (* A233137 *)
%t A233136 Flatten[t] (* A233138 *)
%t A233136 Table[FromDigits[Reverse[u[n]]], {n, 1, 30}] (* A233135 *)
%t A233136 Flatten[Table[Reverse[u[n]], {n, 1, 30}]] (* A233136 *)
%Y A233136 Cf. A040039, A135529, A232559, A000045, A233135, A233137, A233138.
%K A233136 nonn,easy
%O A233136 1,2
%A A233136 _Clark Kimberling_, Dec 05 2013