A191618 Least a such that (2^n+a)*2^n - 1 is prime.

0, 1, 1, 1, 2, 1, 11, 2, 2, 1, 13, 2, 4, 22, 2, 1, 2, 2, 43, 4, 2, 13, 2, 1, 13, 1, 2, 46, 8, 29, 83, 2, 8, 34, 1, 11, 19, 31, 25, 7, 38, 31, 31, 76, 52, 31, 43, 32, 13, 92, 2, 1, 59, 22, 1, 16, 19, 11, 16, 74, 8, 13, 8, 74, 2, 121, 20, 49, 85, 134, 116, 16

Offset: 1

Author

Pierre CAMI, Jun 09 2011

Keywords

• nonn

Links

• Pierre CAMI, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A191617, A191619, A191620, A191621.

Programs

Mathematica

Table[a = 0; While[! PrimeQ[(2^n + a)*2^n - 1], a++]; a, {n, 100}] (* T. D. Noe, Jun 11 2011 *)