A098171 Least j such that P(n)#/2 + 2*P(j) is prime with j > 1 except j=1 for n=1.

1, 3, 4, 5, 6, 8, 10, 11, 10, 11, 13, 13, 14, 23, 17, 23, 38, 25, 44, 24, 24, 40, 30, 28, 32, 37, 32, 29, 30, 91, 36, 52, 39, 56, 51, 47, 54, 39, 109, 46, 46, 47, 65, 53, 97, 154, 63, 49, 81, 92, 66, 57, 119, 60, 63, 59, 95, 75, 63, 83, 154, 70, 79, 70, 66, 105, 74, 77, 79, 91

Offset

1,2

Links

Table of n, a(n) for n=1..70.

Mathematica

Primorial[n_Integer] := Block[{k = Product[Prime[j], {j, n}]}, k]; f[n_] := Block[{p = Primorial[n]/2}, If[n == 1, j = 1, j = 2]; While[ !PrimeQ[p + 2Prime[j]], j++ ]; j]; Table[ f[n], {n, 70}] (* Robert G. Wilson v, Sep 04 2004 *)

Crossrefs

The P(j) sequence is given in A098170.

Sequence in context: A376608 A103605 A375593 * A039031 A047309 A121502

Adjacent sequences: A098168 A098169 A098170 * A098172 A098173 A098174

Keyword

nonn

Author

Pierre CAMI, Aug 30 2004

Extensions

Edited, corrected and extended by Robert G. Wilson v, Sep 04 2004

Status

approved