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Positions of 2 in A287407.
5

%I #4 May 26 2017 16:42:54

%S 3,4,7,10,13,18,19,24,25,28,33,34,37,40,45,48,49,52,55,60,61,66,67,70,

%T 73,76,81,82,87,88,93,94,97,100,103,108,109,114,115,118,121,126,129,

%U 130,133,138,139,142,145,148,153,154,159,160,163,168,169,174,175

%N Positions of 2 in A287407.

%C a(n) - a(n-1) is in {1,3,5} for n >= 1; also, 3n - a(n) is in {0, 2} for n >= 1. The first 20 numbers 3n - a(n) are 0, 2, 2, 2, 2, 0, 2, 0, 2, 2, 0, 2, 2, 2, 0, 0, 2, 2, 2, 0, with 0 in positions given by A287408.

%H Clark Kimberling, <a href="/A287410/b287410.txt">Table of n, a(n) for n = 1..10000</a>

%t s = Nest[Flatten[# /. {0->{0, 1, 2}, 1->{2, 1, 0}, 2->{2, 0, 1}}] &, {0}, 9]; (*A287407*)

%t Flatten[Position[s, 0]]; (*A287408*)

%t Flatten[Position[s, 1]]; (*A287409*)

%t Flatten[Position[s, 2]]; (*A287410*)

%Y Cf. A287407, A287408, A287409.

%K nonn,easy

%O 1,1

%A _Clark Kimberling_, May 25 2017