A201360 Numbers k such that (2^k - k + 1)*2^k + 1 is prime.

1, 2, 39, 44, 62, 1478, 2306, 35335

Offset

1,2

Links

Table of n, a(n) for n=1..8.

Example

2 is in the sequence because (2^2 - 2 + 1)*2^2 + 1 = 13 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, A201361, A201362, A201363.

Sequence in context: A062982 A042801 A078733 * A227904 A175760 A080920

Adjacent sequences: A201357 A201358 A201359 * A201361 A201362 A201363

Keyword

nonn,hard,more

Author

Michel Lagneau, Nov 30 2011

Extensions

a(8) from Michael S. Branicky, May 12 2023

Status

approved