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 A287181 #4 May 23 2017 14:32:00
%S A287181 1,2,4,5,9,11,12,14,15,19,25,27,28,32,34,35,37,38,42,44,45,47,48,52,
%T A287181 58,60,61,65,71,77,79,80,84,86,87,89,90,94,100,102,103,107,109,110,
%U A287181 112,113,117,119,120,122,123,127,133,135,136,140,142,143,145,146
%N A287181 Positions of 1 in A287179.
%H A287181 Clark Kimberling, <a href="/A287181/b287181.txt">Table of n, a(n) for n = 1..10000</a>
%t A287181 s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {2, 0}, 2 -> 1}] &, {0}, 9] (* A287179 *)
%t A287181 Flatten[Position[s, 0]] (* A287180 *)
%t A287181 Flatten[Position[s, 1]] (* A287181 *)
%t A287181 Flatten[Position[s, 2]] (* A287182 *)
%Y A287181 Cf. A287179, A287180, A287182.
%K A287181 nonn,easy
%O A287181 1,2
%A A287181 _Clark Kimberling_, May 22 2017