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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
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, 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, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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.

LINKS

Table of n, a(n) for n=1..89.

MATHEMATICA

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

CROSSREFS

Sequence in context: A220420 A190616 A238018 * A070674 A070668 A318407

Adjacent sequences:  A131639 A131640 A131641 * A131643 A131644 A131645

KEYWORD

nonn

AUTHOR

Giovanni Teofilatto, Sep 08 2007

EXTENSIONS

Edited, corrected and extended by Stefan Steinerberger, Sep 26 2007

STATUS

approved

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Last modified August 23 13:56 EDT 2019. Contains 326228 sequences. (Running on oeis4.)