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 A071928 #23 Apr 03 2025 14:12:23
%S A071928 2,2,4,4,2,2,2,2,4,4,4,4,2,2,4,4,2,2,4,4,2,2,2,2,4,4,4,4,2,2,2,2,4,4,
%T A071928 4,4,2,2,4,4,2,2,2,2,4,4,4,4,2,2,4,4,2,2,2,2,4,4,4,4,2,2,4,4,2,2,4,4,
%U A071928 2,2,2,2,4,4,4,4,2,2,2,2,4,4,4,4,2,2,4,4,2,2,4,4,2,2,2,2,4,4,4,4,2,2,2,2,4
%N A071928 Kolakoski-(2,4) sequence: a(n) is length of n-th run.
%H A071928 Ivan Neretin, <a href="/A071928/b071928.txt">Table of n, a(n) for n = 1..10000</a>
%H A071928 Michael Baake and Bernd Sing, <a href="http://arxiv.org/abs/math/0206098">Kolakoski-(3,1) is a (deformed) model set</a>, arXiv:math/0206098 [math.MG], 2002-2003.
%H A071928 Bernd Sing, <a href="http://arxiv.org/abs/math-ph/0207037">Kolakoski-(2m,2n) are limit-periodic model sets</a>, arXiv:math-ph/0207037, 2002-2003.
%F A071928 Generated by infinitely iterating the morphism a->abc, b->dab, c->efg, d->hcd, e->cda, f->bef, g->ghc, h->dab starting with a, obtaining the infinite word abcdabefg..., and then replacing a,b,e,f by 2 and c,d,g,h by 4. - _Jeffrey Shallit_, Dec 31 2024
%t A071928 seed = {2, 4}; w = {}; i = 1; Do[w = Join[w,Array[seed[[Mod[i - 1, Length[seed]] + 1]] &, If[i > Length[w], seed, w][[i]]]]; i++, {n, 36}]; w (* _Ivan Neretin_, Apr 02 2015 *)
%Y A071928 Cf. A000002, A071820, A071907, A064353, A071942.
%K A071928 nonn,easy
%O A071928 1,1
%A A071928 _N. J. A. Sloane_
%E A071928 More terms from Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Sep 08 2002