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 A287180 #4 May 23 2017 14:31:46
%S A287180 3,6,8,10,13,16,18,20,22,24,26,29,31,33,36,39,41,43,46,49,51,53,55,57,
%T A287180 59,62,64,66,68,70,72,74,76,78,81,83,85,88,91,93,95,97,99,101,104,106,
%U A287180 108,111,114,116,118,121,124,126,128,130,132,134,137,139,141
%N A287180 Positions of 0 in A287179.
%H A287180 Clark Kimberling, <a href="/A287180/b287180.txt">Table of n, a(n) for n = 1..10000</a>
%t A287180 s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {2, 0}, 2 -> 1}] &, {0}, 9] (* A287179 *)
%t A287180 Flatten[Position[s, 0]] (* A287180 *)
%t A287180 Flatten[Position[s, 1]] (* A287181 *)
%t A287180 Flatten[Position[s, 2]] (* A287182 *)
%Y A287180 Cf. A287179, A287181, A287182.
%K A287180 nonn,easy
%O A287180 1,1
%A A287180 _Clark Kimberling_, May 22 2017