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 A287528 #7 Jun 01 2017 21:09:55
%S A287528 0,1,2,1,0,2,2,1,0,1,0,2,0,1,2,2,1,0,2,1,0,1,0,2,0,1,2,1,0,2,0,1,2,2,
%T A287528 1,0,0,1,2,1,0,2,2,1,0,2,1,0,1,0,2,0,1,2,2,1,0,1,0,2,0,1,2,1,0,2,0,1,
%U A287528 2,2,1,0,0,1,2,1,0,2,2,1,0,1,0,2,0,1
%N A287528 Start with 0 and repeatedly substitute 0->012, 1->102, 2->210.
%C A287528 This is the fixed point of the morphism 0->012, 1->102, 2->201 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 A287528 See A287385 for a guide to related sequences.
%H A287528 Clark Kimberling, <a href="/A287528/b287528.txt">Table of n, a(n) for n = 1..10000</a>
%H A287528 <a href="/index/Fi#FIXEDPOINTS">Index entries for sequences that are fixed points of mappings</a>
%e A287528 First three iterations of the morphism: 012, 012102210, 012102210102012210210102012.
%t A287528 s = Nest[Flatten[# /. {0->{0, 1, 2}, 1->{1, 0, 2}, 2->{2, 1, 0}}] &, {0}, 9]; (*A287528*)
%t A287528 Flatten[Position[s, 0]]; (*A287529*)
%t A287528 Flatten[Position[s, 1]]; (*A189670*)
%t A287528 Flatten[Position[s, 2]]; (*A189634*)
%Y A287528 Cf. A189670, A287528, A287529, A189634.
%K A287528 nonn,easy
%O A287528 1,3
%A A287528 _Clark Kimberling_, May 30 2017