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 A287455 #10 Jun 01 2022 18:09:26
%S A287455 0,1,2,2,0,1,2,1,0,2,1,0,0,1,2,2,0,1,2,1,0,2,0,1,0,1,2,2,1,0,2,0,1,0,
%T A287455 1,2,0,1,2,2,0,1,2,1,0,2,1,0,0,1,2,2,0,1,2,1,0,2,0,1,0,1,2,2,1,0,0,1,
%U A287455 2,2,0,1,0,1,2,2,0,1,2,1,0,2,1,0,2,0
%N A287455 Start with 0 and repeatedly substitute 0->012, 1->201, 2->210.
%C A287455 This is the fixed point of the morphism 0->012, 1->201, 2->210 starting with 0. Let u be the (nonperiodic) sequence of positions of 0, and likewise, v for 1 and w for 2; then u(n)/n -> 3, v(n)/n -> 3, w(n)/n -> 3.
%C A287455 See A287385 for a guide to related sequences.
%H A287455 Clark Kimberling, <a href="/A287455/b287455.txt">Table of n, a(n) for n = 1..10000</a>
%H A287455 <a href="/index/Fi#FIXEDPOINTS">Index entries for sequences that are fixed points of mappings</a>
%e A287455 First three iterations of the morphism: 012, 012201210, 012201210210012201210201012.
%t A287455 s = Nest[Flatten[# /. {0->{0, 1, 2}, 1->{2, 0, 1}, 2->{2, 1, 0}}] &, {0}, 9]; (*A287455*)
%t A287455 Flatten[Position[s, 0]]; (*A287456*)
%t A287455 Flatten[Position[s, 1]]; (*A287457*)
%t A287455 Flatten[Position[s, 2]]; (*A287458*)
%Y A287455 Cf. A287385, A287456, A287457, A287458.
%K A287455 nonn,easy
%O A287455 1,3
%A A287455 _Clark Kimberling_, May 30 2017