%I #4 May 31 2017 21:23:50

%S 1,7,12,14,20,22,25,31,35,40,42,45,50,53,59,64,67,72,74,77,82,85,91,

%T 96,97,103,108,110,116,118,121,127,132,134,137,143,147,152,154,157,

%U 162,165,171,176,177,183,188,190,194,197,203,208,209,215,220,222,228

%N Positions of 0 in A287561.

%C 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 3, 1, 0, 2, 0, 2, 3, 1, 1, 0, 2, 3, 2, 3, 1, 0, 1, 0, 2, 3, with

%C 0 in positions given by A287563,

%C 1 in positions given by A287564,

%C 2 in positions given by A287565,

%C 3 in positions given by A287562.

%H Clark Kimberling, <a href="/A287562/b287562.txt">Table of n, a(n) for n = 1..10000</a>

%t s = Nest[Flatten[# /. {0 -> {0, 2, 1, 3}, 1 -> {2, 1, 3, 0}, 2 -> {1, 3, 0, 2}, 3 -> {3, 0, 2, 1}}] &, {0}, 9]; (* A287561 *)

%t Flatten[Position[s, 0]]; (* A287562 *)

%t Flatten[Position[s, 1]]; (* A287563 *)

%t Flatten[Position[s, 2]]; (* A287564 *)

%t Flatten[Position[s, 3]]; (* A287565 *)

%Y Cf. A287561, A287563, A287564, A287565.

%K nonn,easy

%O 1,2

%A _Clark Kimberling_, May 31 2017