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 A287174 #5 May 22 2017 20:03:33 %S A287174 2,0,1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,0,1,0,2,0,1,0,1,0,2, %T A287174 0,1,0,0,1,0,2,0,1,0,2,0,1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0, %U A287174 1,0,2,0,1,0,0,1,0,2,0,1,0,2,0,1,0,0 %N A287174 2-limiting word of the morphism 0->10, 1->20, 2->0. %C A287174 Starting with 0, the first 5 iterations of the morphism yield words shown here: %C A287174 1st: 10 %C A287174 2nd: 2010 %C A287174 3rd: 0102010 %C A287174 4th: 1020100102010 %C A287174 5th: 201001020101020100102010 %C A287174 The 2-limiting word is the limit of the words for which the number of iterations is congruent to 2 mod 3. %C A287174 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 A287174 U = 1.8392867552141611325518525646532866..., %C A287174 V = U^2 = 3.3829757679062374941227085364..., %C A287174 W = U^3 = 6.2222625231203986266745611011.... %C A287174 If n >=2, then u(n) - u(n-1) is in {1,2}, v(n) - v(n-1) is in {2,3,4}, and w(n) - w(n-1) is in {4,6,7}. %H A287174 Clark Kimberling, <a href="/A287174/b287174.txt">Table of n, a(n) for n = 1..10000</a> %e A287174 2nd iterate: 2010 %e A287174 5th iterate: 201001020101020100102010 %t A287174 s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {2, 0}, 2 -> 0}] &, {0}, 11] (* A287174 *) %t A287174 Flatten[Position[s, 0]] (* A287175 *) %t A287174 Flatten[Position[s, 1]] (* A287176 *) %t A287174 Flatten[Position[s, 2]] (* A287177 *) %Y A287174 Cf. A286998, A287111, A287175, A287176, A287177. %K A287174 nonn,easy %O A287174 1,1 %A A287174 _Clark Kimberling_, May 22 2017