A098857 - OEIS

%I #16 Oct 04 2024 11:23:54

%S 1,2,18,40,50,60,62,2688,2880,23678,35076

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

%o (PARI) is(n)=ispseudoprime(4^n*(2^n-1)-1) \\ _Charles R Greathouse IV_, Jun 13 2017

%o (Magma) [k: k in [1..100] | IsPrime(4^k*(2^k-1)-1)]; // _Jinyuan Wang_, Mar 19 2020

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

%K nonn,more

%O 1,2

%A _Pierre CAMI_, Oct 11 2004

%E a(10) from _Ray G. Opao_, Sep 19 2005

%E a(11) from _Michael S. Branicky_, Oct 04 2024