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%I #4 May 25 2017 13:15:11
%S 3,4,8,11,13,18,21,23,25,30,32,34,38,40,45,48,49,53,57,58,62,66,68,70,
%T 74,76,81,84,85,89,93,95,97,101,103,108,111,113,115,119,121,126,129,
%U 130,134,138,139,143,146,148,153,156,158,160,165,166,170,173,175
%N Positions of 2 in A287385.
%C a(n) - a(n-1) is in {1,2,3,4,5} for n >= 1; also, 3n - a(n) is in {0,1,2} for n >= 1. The first 20 numbers 3n - a(n) are 0, 2, 1, 1, 2, 0, 0, 1, 2, 0, 1, 2, 1, 2, 0, 0, 2, 1, 0, 2, with 0 in positions given by A287386.
%H Clark Kimberling, <a href="/A287388/b287388.txt">Table of n, a(n) for n = 1..10000</a>
%t s = Nest[Flatten[# /. {0->{0, 1, 2}, 1->{2, 1, 0}, 2->{0, 2, 1}}] &, {0}, 9]; (*A287385*)
%t Flatten[Position[s, 0]]; (*A287386*)
%t Flatten[Position[s, 1]]; (*A287387*)
%t Flatten[Position[s, 2]]; (*A287388*)
%Y Cf. A287385, A287386, A287387.
%K nonn,easy
%O 1,1
%A _Clark Kimberling_, May 25 2017