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 A287000 #4 May 22 2017 20:02:51
%S A287000 2,6,8,12,15,19,23,26,30,32,36,39,43,45,49,52,56,60,63,67,69,73,76,80,
%T A287000 83,87,89,93,96,100,104,107,111,113,117,120,124,128,131,135,137,141,
%U A287000 144,148,151,155,157,161,164,168,172,175,179,181,185,188,192,194
%N A287000 Positions of 1 in A286998.
%H A287000 Clark Kimberling, <a href="/A287000/b287000.txt">Table of n, a(n) for n = 1..10000</a>
%t A287000 s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {2, 0}, 2 -> 0}] &, {0}, 9] (* A286998 *)
%t A287000 Flatten[Position[s, 0]] (* A286999 *)
%t A287000 Flatten[Position[s, 1]] (* A287000 *)
%t A287000 Flatten[Position[s, 2]] (* A287001 *)
%Y A287000 Cf. A286998, A286999, A287001.
%K A287000 nonn,easy
%O A287000 1,1
%A A287000 _Clark Kimberling_, May 22 2017