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 A287160 #4 May 22 2017 12:23:42 %S A287160 0,2,1,2,1,1,0,2,1,1,0,1,0,0,2,1,2,1,1,0,1,0,0,2,1,1,0,0,2,1,0,2,1,2, %T A287160 1,1,0,2,1,1,0,1,0,0,2,1,1,0,0,2,1,0,2,1,2,1,1,0,1,0,0,2,1,0,2,1,2,1, %U A287160 1,0,0,2,1,2,1,1,0,2,1,1,0,1,0,0,2,1 %N A287160 0-limiting word of the morphism 0->10, 1->21, 2->0. %C A287160 Starting with 0, the first 4 iterations of the morphism yield words shown here: %C A287160 1st: 10 %C A287160 2nd: 2110 %C A287160 3rd: 0212110 %C A287160 4th: 1002010212110 %C A287160 The 0-limiting word is the limit of the words for which the number of iterations is congruent to 0 mod 3. %C A287160 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 A287160 U = 3.079595623491438786010417..., %C A287160 V = 2.324717957244746025960908..., %C A287160 W = U + 1 = 4.079595623491438786010417.... %C A287160 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 A287160 Clark Kimberling, <a href="/A287160/b287160.txt">Table of n, a(n) for n = 1..10000</a> %e A287160 The 3rd and 6th iterates are 0212110 and 0212110211010021211010021100210212110. %t A287160 s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {2, 1}, 2 -> 0}] &, {0}, 9] (* A287160 *) %t A287160 Flatten[Position[s, 0]] (* A287161 *) %t A287160 Flatten[Position[s, 1]] (* A287162 *) %t A287160 Flatten[Position[s, 2]] (* A287163 *) %Y A287160 Cf. A287106, A287156, A287161, A287162, A287163. %K A287160 nonn,easy %O A287160 1,2 %A A287160 _Clark Kimberling_, May 22 2017