A111296 Smallest prime of the form n*k + 1, where each k may be used in the sequence only once.

2, 5, 13, 13, 31, 31, 71, 73, 73, 71, 199, 157, 157, 197, 241, 241, 409, 199, 419, 401, 547, 419, 691, 409, 701, 547, 919, 701, 929, 691, 1117, 929, 1321, 919, 1471, 1117, 1777, 1483, 1483, 1321, 2297, 1471, 1979, 2069, 2251, 1979, 2069, 1777, 2549, 2251

Offset

1,1

Links

Table of n, a(n) for n=1..50.

Example

a(10) = 10*13 + 1 = 131 though 10*10 + 1 = 101 is also prime but k=10 has already been used by n=7.

Mathematica

l = {}; Do[k = 1; While[MemberQ[l, k] || !PrimeQ[n*k + 1], k++ ]; Print[n*k+1]; AppendTo[l, k], {n, 30}] (* Ryan Propper, Jun 15 2006 *)

Crossrefs

Cf. A087559.

Sequence in context: A067365 A189993 A112838 * A089728 A127987 A247543

Adjacent sequences: A111293 A111294 A111295 * A111297 A111298 A111299

Keyword

nonn

Author

Amarnath Murthy, Nov 11 2005

Extensions

Corrected and extended by Ryan Propper, Jun 15 2006

More terms from R. J. Mathar, Aug 20 2007

Status

approved