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

Offset: 1

Author

Robert G. Wilson v, Jan 11 2006

Keywords

• nonn

Crossrefs

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

Programs

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 *)