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A179835 Smallest k > 0 such that prime(n-k) + prime(n+k) = 2*prime(n), or 0 if there is no such k. 2
0, 0, 1, 0, 2, 2, 2, 0, 0, 3, 3, 6, 3, 0, 0, 1, 7, 4, 8, 3, 0, 0, 7, 4, 6, 6, 2, 2, 0, 0, 6, 8, 7, 12, 0, 2, 1, 0, 6, 1, 2, 4, 8, 15, 15, 0, 1, 0, 0, 0, 6, 0, 0, 2, 1, 1, 0, 0, 6, 0, 0, 0, 19, 7, 0, 0, 17, 5, 29, 3, 15, 15, 5, 1, 5, 20, 20, 4, 7, 2, 21, 2, 21, 4, 3, 5, 4, 27, 3, 0, 0, 5, 28, 2, 0, 0, 0, 21, 0, 30 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

MATHEMATICA

nn=1000; p=Prime[Range[2*nn]]; Table[s=Take[p, n-1] + Reverse[Take[p, {n+1, 2n-1}]]; pos=Position[s, 2*p[[n]]]; If[pos=={}, 0, n-pos[[-1, 1]]], {n, nn}]

CROSSREFS

Cf. A178609 (largest k), A178670 (number of k)

Sequence in context: A034852 A212438 A112790 * A110857 A108867 A218604

Adjacent sequences:  A179832 A179833 A179834 * A179836 A179837 A179838

KEYWORD

nonn

AUTHOR

T. D. Noe, Jan 10 2011

STATUS

approved

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Last modified October 16 00:50 EDT 2018. Contains 316252 sequences. (Running on oeis4.)