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A112686
Smallest prime p such that the sum of the predecessor and successor primes is divisible by n.
1
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
1,1
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 *)
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jan 11 2006
STATUS
approved