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 A287108 #10 May 26 2017 21:31:47 %S A287108 1,0,0,2,1,0,2,1,2,1,1,0,0,2,1,2,1,1,0,2,1,1,0,1,0,0,2,1,0,2,1,2,1,1, %T A287108 0,2,1,1,0,1,0,0,2,1,2,1,1,0,1,0,0,2,1,1,0,0,2,1,0,2,1,2,1,1,0,0,2,1, %U A287108 2,1,1,0,2,1,1,0,1,0,0,2,1,2,1,1,0,1 %N A287108 1-limiting word of the morphism 0->10, 1->21, 2->0. %C A287108 Starting with 0, the first 4 iterations of the morphism yield words shown here: %C A287108 1st: 10 %C A287108 2nd: 2110 %C A287108 3rd: 0212110 %C A287108 4th: 100210212110 %C A287108 The 1-limiting word is the limit of the words for which the number of iterations is congruent to 1 mod 3. %C A287108 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 A287108 U = 3.079595623491438786010417..., %C A287108 V = 2.324717957244746025960908..., %C A287108 W = U + 1 = 4.079595623491438786010417.... %C A287108 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}. %H A287108 Clark Kimberling, <a href="/A287108/b287108.txt">Table of n, a(n) for n = 1..10000</a> %e A287108 The 1st, 4th, and 7th iterates are %e A287108 10, 100210212110, 10021021211002121102110100210212110211010021211010021100210212110. %t A287108 s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {2, 1}, 2 -> 0}] &, {0}, 10] (* A287108 *) %t A287108 Flatten[Position[s, 0]] (* A287109 *) %t A287108 Flatten[Position[s, 1]] (* A287110 *) %t A287108 Flatten[Position[s, 2]] (* A287111 *) %Y A287108 Cf. A287109, A287110, A287111. %K A287108 nonn,easy %O A287108 1,4 %A A287108 _Clark Kimberling_, May 21 2017