A112686 - OEIS

A112686

Smallest prime p such that the sum of the predecessor and successor primes is divisible by n.

3, 5, 23, 7, 5, 23, 3, 7, 29, 5, 31, 23, 79, 13, 73, 7, 151, 29, 59, 11, 61, 31, 229, 23, 73, 79, 29, 13, 149, 73, 311, 17, 31, 151, 71, 37, 181, 59, 79, 19, 283, 61, 521, 43, 89, 229, 1277, 23, 197, 73, 151, 79, 53, 29, 109, 83, 59, 149, 113, 89, 127, 311, 61, 383, 389, 31

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..66.

MATHEMATICA

f[n_] := Block[{k = 2}, While[ Mod[ Prime[k - 1] + Prime[k + 1], n] != 0, k++ ]; Prime[k]]; Array[f, 66]

With[{prs=Partition[Prime[Range[250]], 3, 1]}, Transpose[Flatten[ Table[ Select[ prs, Divisible[ First[#]+Last[#], n]&, 1], {n, 70}], 1]][[2]]] (* Harvey P. Dale, Jan 16 2014 *)

CROSSREFS

Cf. A000040, A112545, A112681, A112794, A112731, A112789, A112795, A112796, A112804, A112847, A112859, A113155, A113156, A113157, A113158.

Sequence in context: A270621 A270637 A064187 * A318443 A272426 A270180

Adjacent sequences: A112683 A112684 A112685 * A112687 A112688 A112689

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Jan 11 2006

STATUS

approved