A126608 Smallest odd prime q such that pq+2 is prime, where p is the n-th odd prime.

3, 3, 3, 7, 3, 3, 3, 3, 3, 5, 3, 61, 3, 7, 7, 3, 5, 5, 7, 5, 3, 3, 3, 3, 7, 3, 7, 5, 13, 3, 7, 13, 3, 3, 5, 5, 3, 3, 3, 43, 5, 19, 5, 3, 3, 29, 5, 3, 11, 3, 3, 17, 7, 3, 19, 3, 41, 11, 31, 17, 3, 41, 7, 3, 3, 5, 3, 13, 3, 3, 19, 3, 5, 23, 3, 13, 3, 19, 3, 3, 17, 7, 3, 3, 19, 13, 3, 7, 17, 7, 3, 5, 37, 3

Offset

1,1

Links

Table of n, a(n) for n=1..94.

Mathematica

f[n_] := Block[{p = Prime[n + 1], k = 1, q}, While[q = Prime[k + 1]; ! PrimeQ[p*q + 2], k++ ]; q]; Table[f[n], {n, 95}] (* Ray Chandler, Feb 07 2007

Crossrefs

Cf. A126609.

Sequence in context: A079988 A212091 A061021 * A088195 A131757 A214834

Adjacent sequences: A126605 A126606 A126607 * A126609 A126610 A126611

Keyword

nonn,easy

Author

N. J. A. Sloane, Feb 06 2007

Extensions

Extended by Ray Chandler, Feb 07 2007

Status

approved