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 A287573 #4 Jun 01 2017 21:08:50
%S A287573 3,8,10,13,17,23,28,30,36,38,41,47,50,53,59,64,66,69,75,80,83,88,90,
%T A287573 93,97,103,108,110,116,118,121,127,129,135,140,142,148,150,153,159,
%U A287573 162,165,171,176,179,184,186,189,196,198,201,207,210,213,219,224,227
%N A287573 Positions of 1 in A287571.
%C A287573 a(n) - a(n-1) is in {1,2,3,4,5,6,7} for n >= 1; also, 4n - a(n) is in {0,1,2,3} for n >= 1. The first 20 numbers 4n - a(n) are 1, 0, 2, 3, 3, 1, 0, 2, 0, 2, 3, 1, 2, 3, 1, 0, 2, 3, 1, 0, with
%C A287573 0 in positions given by A287575,
%C A287573 1 in positions given by A287572,
%C A287573 2 in positions given by A287573,
%C A287573 3 in positions given by A287574.
%H A287573 Clark Kimberling, <a href="/A287573/b287573.txt">Table of n, a(n) for n = 1..10000</a>
%t A287573 s = Nest[Flatten[# /. {0 -> {0,3,1,2}, 1 -> {3,1,2,0}, 2 -> {1,2,0,3}, 3 -> {2,0,3,1}}] &, {0}, 9]; (* A287571 *)
%t A287573 Flatten[Position[s, 0]]; (* A287572 *)
%t A287573 Flatten[Position[s, 1]]; (* A287573 *)
%t A287573 Flatten[Position[s, 2]]; (* A287574 *)
%t A287573 Flatten[Position[s, 3]]; (* A287575 *)
%Y A287573 Cf. A287571, A287572, A287574, A287575.
%K A287573 nonn,easy
%O A287573 1,1
%A A287573 _Clark Kimberling_, Jun 01 2017