A098857 Numbers k such that 4^k*(2^k - 1) - 1 is prime.

1, 2, 18, 40, 50, 60, 62, 2688, 2880, 23678

Offset

1,2

Links

Table of n, a(n) for n=1..10.

Prog

(PARI) is(n)=ispseudoprime(4^n*(2^n-1)-1) \\ Charles R Greathouse IV, Jun 13 2017
(Magma) [k: k in [1..100] | IsPrime(4^k*(2^k-1)-1)]; // Jinyuan Wang, Mar 19 2020

Crossrefs

Cf. A098856 ((4^k)*(2^k - 1) + 1 is prime).

Sequence in context: A099904 A137308 A050594 * A189333 A072278 A296266

Adjacent sequences: A098854 A098855 A098856 * A098858 A098859 A098860

Keyword

nonn,more

Author

Pierre CAMI, Oct 11 2004

Extensions

a(10) from Ray G. Opao, Sep 19 2005

Status

approved