%I #4 May 17 2017 17:58:05
%S 1,2,5,6,9,10,11,14,15,18,19,20,23,24,27,28,31,32,33,36,37,40,41,42,
%T 45,46,49,50,53,54,55,58,59,62,63,64,67,68,71,72,73,76,77,80,81,84,85,
%U 86,89,90,93,94,95,98,99,102,103,106,107,108,111,112,115,116
%N Positions of 1 in A286903; complement of A286904.
%C a(n) - a(n-1) is in {1,3} for n>=2, and a(n)/n -> -1 + 2*sqrt(2).
%H Clark Kimberling, <a href="/A286905/b286905.txt">Table of n, a(n) for n = 1..10000</a>
%e As a word, A286804 = 11001100111001100111001..., in which 1 is in positions 1,2,5,6,9,...
%t s = Nest[Flatten[# /. {0 -> 1, 1 -> {1, 1, 0}}] &, {1}, 7] (* A080764 *)
%t w = StringJoin[Map[ToString, s]]
%t w1 = StringReplace[w, {"0" -> "00"}]
%t st = ToCharacterCode[w1] - 48 ; (* A286903 *)
%t Flatten[Position[st, 0]]; (* A286904 *)
%t Flatten[Position[st, 1]]; (* A286905 *)
%Y Cf. A080764, A286903, A286904.
%K nonn,easy
%O 1,2
%A _Clark Kimberling_, May 17 2017
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