%I
%S 4,5,11,14,18,24,25,31,33,39,42,48,51,54,60,61,67,70,76,77,84,85,91,
%T 94,98,104,105,111,113,119,122,128,130,136,137,143,145,151,154,160,
%U 163,166,172,173,180,181,187,190,193,199,202,208,211,214,220,221,228
%N Positions of 2 in A287571.
%C a(n)  a(n1) 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 0, 3, 1, 2, 2, 0, 3, 1, 3, 1, 2, 0, 1, 2, 0, 3, 1, 2, 0, 3, with
%C 0 in positions given by A287572,
%C 1 in positions given by A287573,
%C 2 in positions given by A287574,
%C 3 in positions given by A287575.
%H Clark Kimberling, <a href="/A287574/b287574.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = 4n  A287571(n) for n >= 1.
%t 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 Flatten[Position[s, 0]]; (* A287572 *)
%t Flatten[Position[s, 1]]; (* A287573 *)
%t Flatten[Position[s, 2]]; (* A287574 *)
%t Flatten[Position[s, 3]]; (* A287575 *)
%Y Cf. A287571, A287572, A287573, A287575.
%K nonn,easy
%O 1,1
%A _Clark Kimberling_, Jun 01 2017
