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 A287202 #4 May 23 2017 21:00:14
%S A287202 3,7,9,11,17,21,25,27,29,35,37,39,45,47,49,55,61,67,71,75,77,79,85,89,
%T A287202 93,95,97,103,107,111,113,115,121,123,125,131,133,135,141,147,153,157,
%U A287202 161,163,165,171,173,175,181,183,185,191,197,203,207,211,213,215
%N A287202 Positions of 1 in A287200.
%H A287202 Clark Kimberling, <a href="/A287202/b287202.txt">Table of n, a(n) for n = 1..10000</a>
%t A287202 s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {2, 2}, 2 -> 0}] &, {0}, 11] (* A287200 *)
%t A287202 Flatten[Position[s, 0]] (* A287201 *)
%t A287202 Flatten[Position[s, 1]] (* A287202 *)
%t A287202 Flatten[Position[s, 2]] (* A287203 *)
%Y A287202 Cf. A287200, A287201, A287203.
%K A287202 nonn,easy
%O A287202 1,1
%A A287202 _Clark Kimberling_, May 23 2017