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 A287066 #12 May 29 2017 23:57:22
%S A287066 1,2,0,0,1,0,1,1,2,0,1,1,2,1,2,0,0,1,1,2,1,2,0,1,2,0,0,1,0,1,1,2,1,2,
%T A287066 0,1,2,0,0,1,1,2,0,0,1,0,1,1,2,0,1,1,2,1,2,0,1,2,0,0,1,1,2,0,0,1,0,1,
%U A287066 1,2,1,2,0,0,1,0,1,1,2,0,1,1,2,1,2,0
%N A287066 Start with 1 and repeatedly substitute 0->01, 1->12, 2->0.
%C A287066 This is the fixed point of the morphism 0->01, 1->12, 2->0 starting with 1. Let u be the sequence of positions of 0, and likewise, v for 1 and w for 2. Let U, V, W be the limits of u(n)/n, v(n)/n, w(n)/n, respectively. Then 1/U + 1/V + 1/W = 1, where
%C A287066 U = 3.079595623491438786010417...,
%C A287066 V = 2.324717957244746025960908...,
%C A287066 W = U + 1 = 4.079595623491438786010417....
%C A287066 If n >=2, then u(n) - u(n-1) is in {1,2,3,4,6}, v(n) - v(n-1) is in {1,2,3,4}, and w(n) - w(n-1) is in {2,3,4,5,7}. For n >= 1, the number of terms resulting from n iterations of the morphism is A005251(n+2).
%H A287066 Clark Kimberling, <a href="/A287066/b287066.txt">Table of n, a(n) for n = 1..10000</a>
%H A287066 <a href="/index/Fi#FIXEDPOINTS">Index entries for sequences that are fixed points of mappings</a>
%t A287066 s = Nest[Flatten[# /. {0 -> {0, 1}, 1 -> {1, 2}, 2 -> 0}] &, {1}, 10] (* A287066 *)
%t A287066 Flatten[Position[s, 0]] (* A287067 *)
%t A287066 Flatten[Position[s, 1]] (* A287068 *)
%t A287066 Flatten[Position[s, 2]] (* A287069 *)
%Y A287066 Cf. A057985, A287067, A287068, A287069.
%K A287066 nonn,easy
%O A287066 1,2
%A A287066 _Clark Kimberling_, May 20 2017