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 A287447 #10 Jun 01 2017 10:16:04
%S A287447 0,1,2,2,0,1,1,0,2,1,0,2,0,1,2,2,0,1,2,0,1,0,1,2,1,0,2,2,0,1,0,1,2,1,
%T A287447 0,2,0,1,2,2,0,1,1,0,2,1,0,2,0,1,2,2,0,1,1,0,2,0,1,2,2,0,1,0,1,2,2,0,
%U A287447 1,1,0,2,2,0,1,0,1,2,1,0,2,1,0,2,0,1
%N A287447 Start with 0 and repeatedly substitute 0->012, 1->201, 2->102.
%C A287447 This is the fixed point of the morphism 0->012, 1->201, 2->102 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 A287447 See A287385 for a guide to related sequences.
%H A287447 Clark Kimberling, <a href="/A287447/b287447.txt">Table of n, a(n) for n = 1..10000</a>
%H A287447 <a href="/index/Fi#FIXEDPOINTS">Index entries for sequences that are fixed points of mappings</a>
%e A287447 First three iterations of the morphism: 012, 012201102, 012201102102012201201012102.
%t A287447 s = Nest[Flatten[# /. {0->{0, 1, 2}, 1->{2, 0, 1}, 2->{1, 0, 2}}] &, {0}, 9]; (*A287447*)
%t A287447 Flatten[Position[s, 0]]; (*A189224*)
%t A287447 Flatten[Position[s, 1]]; (*A287449*)
%t A287447 Flatten[Position[s, 2]]; (*A287450*)
%Y A287447 Cf. A189224, A287385, A287449, A287450.
%K A287447 nonn,easy
%O A287447 1,3
%A A287447 _Clark Kimberling_, May 26 2017