A171580 Least k such that k*(2^n)*((2^n-1)^2) - 1 is a prime number.

2, 2, 4, 3, 4, 5, 1, 6, 1, 5, 4, 3, 6, 5, 9, 7, 4, 5, 15, 19, 4, 27, 4, 12, 6, 38, 30, 5, 27, 13, 15, 2, 10, 7, 4, 7, 9, 32, 10, 2, 10, 33, 10, 2, 75, 17, 4, 5, 6, 12, 21, 6, 150, 14, 7, 11, 30, 27, 51, 29, 70, 58, 10, 10, 37, 45, 79, 212, 177, 17, 4, 33, 16, 54, 24, 20, 222, 105, 9, 83, 10

Offset

1,1

Links

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

Prog

(PARI) a(n) = for(k=1, oo, if(ispseudoprime(k*(2^n)*((2^n-1)^2)-1), return(k))); \\ Jinyuan Wang, Feb 25 2020

Crossrefs

Sequence in context: A140472 A109168 A015134 * A246796 A177235 A079707

Adjacent sequences: A171577 A171578 A171579 * A171581 A171582 A171583

Keyword

nonn

Author

Pierre CAMI, Dec 12 2009

Extensions

Extended by Ray Chandler, Dec 19 2009

Status

approved