A200821 Numbers k such that (2^k + k)*2^k - 1 is prime.

1, 2, 34, 107, 1568, 1933, 3551, 6793, 16967

Offset

1,2

Comments

The generalization of this sequence is possible with the primes of the form (b^n +- k)*b^n +- 1.

Links

Table of n, a(n) for n=1..9.

Henri Lifchitz, New forms of primes

Example

2 is in the sequence because (2^2 + 2)*2^2 - 1 = 23 is prime.

Mathematica

lst={}; Do[If[PrimeQ[(2^n + n)*2^n-1], AppendTo[lst, n]], {n, 10000}]; lst

Prog

(PARI) is(n)=ispseudoprime((2^n+n)<<n-1) \\ Charles R Greathouse IV, Feb 17 2017

Crossrefs

Cf. A200816, A200817, A200818, A200819, A200822, A200823, A200832.

Sequence in context: A349496 A337397 A263226 * A200166 A226407 A226336

Adjacent sequences: A200818 A200819 A200820 * A200822 A200823 A200824

Keyword

nonn,more

Author

Michel Lagneau, Nov 23 2011

Extensions

a(9) from Michael S. Branicky, Jul 13 2023

Status

approved