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 A287200 #9 May 27 2021 17:17:25 %S A287200 2,2,1,0,2,2,1,0,1,0,1,0,0,0,2,2,1,0,2,2,1,0,2,2,1,0,1,0,1,0,0,0,2,2, %T A287200 1,0,1,0,1,0,0,0,2,2,1,0,1,0,1,0,0,0,2,2,1,0,0,0,2,2,1,0,0,0,2,2,1,0, %U A287200 2,2,1,0,2,2,1,0,1,0,1,0,0,0,2,2,1,0 %N A287200 2-limiting word of the morphism 0->10, 1->22, 2->0, starting with 0. %C A287200 Starting with 0, the first 5 iterations of the morphism yield words shown here: %C A287200 1st: 10 %C A287200 2nd: 2210 %C A287200 3rd: 002210 %C A287200 4th: 1010002210 %C A287200 5th: 221022101010002210 %C A287200 The 2-limiting word is the limit of the words for which the number of iterations is congruent to 2 mod 3. %C A287200 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 A287200 U = 2.28537528186132044169516884721360670506..., %C A287200 V = 3.87512979416277882597397059430967806752..., %C A287200 W = 3.28537528186132044169516884721360670506... %C A287200 If n >=2, then u(n) - u(n-1) is in {1,2,4}, v(n) - v(n-1) is in {2,4,6}, and w(n) - w(n-1) is in {1,3,5,9}. %H A287200 Clark Kimberling, <a href="/A287200/b287200.txt">Table of n, a(n) for n = 1..10000</a> %e A287200 2nd iterate: 2210 %e A287200 5th iterate: 221022101010002210 %t A287200 s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {2, 2}, 2 -> 0}] &, {0}, 11] (* A287200 *) %t A287200 Flatten[Position[s, 0]] (* A287201 *) %t A287200 Flatten[Position[s, 1]] (* A287202 *) %t A287200 Flatten[Position[s, 2]] (* A287203 *) %Y A287200 Cf. A287175, A287179, A287201, A287202. %K A287200 nonn,easy %O A287200 1,1 %A A287200 _Clark Kimberling_, May 23 2017 %E A287200 Definition corrected by _Georg Fischer_, May 27 2021