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 A131642 a(n) = A001223(n) if the number A001223(n) appears the first time in A001223, a(n) = 1 otherwise. 0

%I

%S 1,2,1,4,1,1,1,1,6,1,1,1,1,1,1,1,1,1,1,1,1,1,1,8,1,1,1,1,1,14,1,1,1,

%T 10,1,1,1,1,1,1,1,1,1,1,1,12,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,

%U 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1

%N a(n) = A001223(n) if the number A001223(n) appears the first time in A001223, a(n) = 1 otherwise.

%C A001223(2)=2 is the first appearance of 2 in A001223, hence a(2) = 2. A001223(3)=2 appeared earlier for A001223(2)=A001223(3), therefore a(3) = 2.

%t a = {}; b = {}; For[n = 1, n < 90, n++, If[Length[Intersection[b, {Prime[n + 1] - Prime[n]}]] == 0, AppendTo[a, Prime[n + 1] - Prime[n]]; AppendTo[b, a[[ -1]]], AppendTo[a, 1]]]; a

%K nonn

%O 1,2

%A _Giovanni Teofilatto_, Sep 08 2007

%E Edited, corrected and extended by _Stefan Steinerberger_, Sep 26 2007

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Last modified September 21 17:46 EDT 2019. Contains 327273 sequences. (Running on oeis4.)