A137906 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, 1, 1, 1, 4, 1, 27, 14, 34, 6, 132, 97, 1, 500, 1816, 1292, 136, 2445, 15, 1934, 5472, 1584, 2734, 21022, 5870

Offset: 1

Author

Pierre CAMI, Feb 22 2008

Keywords

• nonn
• hard
• more

Examples

			1*(2^2-1)*(1*(2^2-1)-1)-1=5 prime, 2^2-1 first Mersenne prime, a(1)=1;
1*(2^3-1)*(1*(2^3-1)-1)-1=41 prime, 2^3-1 second Mersenne prime, a(2)=1.
		

Crossrefs

Cf. A137907, A137908, A137909.