A201362 Numbers k such that (2^k - k - 1)*2^k + 1 is prime.

2, 7, 11, 13, 14, 20, 37, 53, 71, 132, 140, 613, 641, 665, 757, 788, 1878, 6774, 8777, 14575, 20917, 22352, 35828

Offset

1,1

Links

Table of n, a(n) for n=1..23.

Example

2 is in the sequence because (2^2 - 2 - 1)*2^2 + 1 = 5 is prime.

Mathematica

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

Prog

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

Crossrefs

Cf. A201356, A201357, A201358, A201359, A201360, A201361, A201363.

Sequence in context: A113544 A045173 A230048 * A063976 A064000 A069180

Adjacent sequences: A201359 A201360 A201361 * A201363 A201364 A201365

Keyword

nonn,hard,more

Author

Michel Lagneau, Nov 30 2011

Extensions

a(20)-a(23) from Michael S. Branicky, Jul 12 2023

Status

approved