A098857 - OEIS

A098857

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

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

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OFFSET

1,2

LINKS

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).

KEYWORD

nonn,more

AUTHOR

Pierre CAMI, Oct 11 2004

EXTENSIONS

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

STATUS

approved