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

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

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: A190616 A238018 A368945 * 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