A137907 Least k such that k*(2^p-1)*(k*(2^p-1)-1)+1 is prime, where 2^p-1 runs through the Mersenne primes.

1, 1, 9, 6, 9, 24, 4, 7, 28, 70, 73, 121, 511, 106, 343, 2169, 1423, 2146, 5736, 4444, 2484, 2310, 2679, 25623, 2481, 39213

Offset

1,3

Links

Table of n, a(n) for n=1..26.

Example

1*(2^2-1)*(1*(2^2-1)-1)+1=7 prime, 2^2-1 first Mersenne prime, a(1)=1;
1*(2^3-1)*(1*(2^3-1)-1)+1=43 prime, 2^3-1 second Mersenne prime, a(2)=1.

Crossrefs

Cf. A137906, A137908, A137909.

Sequence in context: A019790 A033186 A146486 * A070164 A063602 A180572

Adjacent sequences: A137904 A137905 A137906 * A137908 A137909 A137910

Keyword

nonn,hard,more

Author

Pierre CAMI, Feb 22 2008

Extensions

Corrected by Pierre CAMI, Jun 16 2012

Status

approved