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 A287111 #8 Jun 04 2020 06:41:10
%S A287111 4,7,9,14,16,20,27,30,32,36,43,45,52,57,60,62,67,69,73,80,82,89,94,97,
%T A287111 99,103,110,115,118,120,127,130,132,137,139,143,150,153,155,159,166,
%U A287111 168,175,180,183,185,189,196,201,204,206,213,216,218,223,225,229
%N A287111 Positions of 2 in A287108.
%H A287111 Clark Kimberling, <a href="/A287111/b287111.txt">Table of n, a(n) for n = 1..10000</a>
%t A287111 s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {2, 1}, 2 -> 0}] &, {0}, 10] (* A287108 *)
%t A287111 Flatten[Position[s, 0]] (* A287109 *)
%t A287111 Flatten[Position[s, 1]] (* A287110 *)
%t A287111 Flatten[Position[s, 2]] (* A287111 *)
%Y A287111 Cf. A287108, A287109, A287110.
%K A287111 nonn,easy
%O A287111 1,1
%A A287111 _Clark Kimberling_, May 22 2017