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 A074803 #10 Apr 03 2015 01:56:28
%S A074803 4,4,4,4,2,2,2,2,4,4,4,4,2,2,2,2,4,4,2,2,4,4,2,2,4,4,4,4,2,2,2,2,4,4,
%T A074803 4,4,2,2,2,2,4,4,2,2,4,4,2,2,4,4,4,4,2,2,2,2,4,4,2,2,4,4,4,4,2,2,2,2,
%U A074803 4,4,2,2,4,4,4,4,2,2,2,2,4,4,4,4,2,2,2,2,4,4,2,2,4,4,2,2,4,4,4,4,2,2,2,2,4
%N A074803 Kolakoski-(4,2) sequence: a(n) is length of n-th run.
%H A074803 Ivan Neretin, <a href="/A074803/b074803.txt">Table of n, a(n) for n = 1..10000</a>
%t A074803 seed = {4, 2}; w = {}; i = 1; Do[w = Join[w, Array[seed[[Mod[i - 1, Length[seed]] + 1]] &, If[i > Length[w], seed, w][[i]]]]; i++, {n, 35}]; w (* _Ivan Neretin_, Apr 02 2015 *)
%Y A074803 Cf. A000002.
%K A074803 nonn
%O A074803 1,1
%A A074803 Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Sep 08 2002