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 A287177 #4 May 22 2017 20:03:55
%S A287177 1,8,14,21,28,34,41,45,52,58,65,71,78,82,89,95,102,109,115,122,126,
%T A287177 133,139,146,153,159,166,170,177,183,190,196,203,207,214,220,227,234,
%U A287177 240,247,251,258,264,271,275,282,288,295,302,308,315,319,326,332,339
%N A287177 Positions of 2 in A287174.
%H A287177 Clark Kimberling, <a href="/A287177/b287177.txt">Table of n, a(n) for n = 1..10000</a>
%t A287177 s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {2, 0}, 2 -> 0}] &, {0}, 11] (* A287174 *)
%t A287177 Flatten[Position[s, 0]] (* A287175 *)
%t A287177 Flatten[Position[s, 1]] (* A287176 *)
%t A287177 Flatten[Position[s, 2]] (* A287177 *)
%Y A287177 Cf. A287174, A287175, A287176.
%K A287177 nonn,easy
%O A287177 1,2
%A A287177 _Clark Kimberling_, May 22 2017