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 A287445 #4 May 29 2017 23:58:41
%S A287445 2,6,9,12,14,18,20,24,27,29,33,36,38,42,45,48,50,54,56,60,63,65,69,72,
%T A287445 75,77,81,83,87,90,92,96,99,102,104,108,110,114,117,120,122,126,128,
%U A287445 132,135,137,141,144,146,150,153,156,158,162,164,168,171,174,176
%N A287445 Positions of 1 in A287443.
%C A287445 a(n) - a(n-1) is in {2, 3, 4} for n >= 1; also, 3n - a(n) is in {0, 1} for n >= 1. The first 20 numbers 3n - a(n) are 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, with 1 in positions given by A287444.
%H A287445 Clark Kimberling, <a href="/A287445/b287445.txt">Table of n, a(n) for n = 1..10000</a>
%t A287445 s = Nest[Flatten[# /. {0->{0, 1, 2}, 1->{2, 0, 1}, 2->{0, 2, 1}}] &, {0}, 9]; (*A287443*)
%t A287445 Flatten[Position[s, 0]]; (*A287444*)
%t A287445 Flatten[Position[s, 1]]; (*A287445*)
%t A287445 Flatten[Position[s, 2]]; (*A287446*)
%Y A287445 Cf. A287443, A287444, A287446.
%K A287445 nonn,easy
%O A287445 1,1
%A A287445 _Clark Kimberling_, May 26 2017