A157333 Least j such that 6*p(j)*M(n)-1 is prime with p(j)=j-th prime and M(n) = Mersenne prime

2, 1, 2, 1, 4, 3, 12, 31, 2, 14, 19, 15, 17, 467, 37, 111, 1382, 4830, 276, 1962, 360, 1749, 2857, 17253, 9414, 11974, 30167, 18822, 21387, 24721

Offset

1,1

Links

Table of n, a(n) for n=1..30.

Example

6*3*(2^2-1)-1=53 prime 2^2-1=M(1) 3=p(2) so j(1)=2 6*2*(2^3-1)-1=83 prime 2^3-1=M(2) 2=p(1) so j(2)=1

Crossrefs

Sequence in context: A088980 A254436 A208548 * A002852 A266081 A188440

Adjacent sequences: A157330 A157331 A157332 * A157334 A157335 A157336

Keyword

nonn

Author

Pierre CAMI, Feb 27 2009

Status

approved