A201363 Numbers k such that (2^k - k - 1)*2^k - 1 is prime.

2, 3, 7, 42066

Offset

1,1

Comments

No further terms less than 10000. - T. D. Noe, Nov 30 2011

Links

Table of n, a(n) for n=1..4.

Example

7 is in the sequence because (2^7 - 7 - 1)*2^7 - 1 = 15359 is prime.

Mathematica

lst={}; Do[If[PrimeQ[(2^n - n-1)*2^n-1], AppendTo[lst, n]], {n, 15000}]; 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, A201362.

Sequence in context: A334021 A196303 A048979 * A088332 A357064 A131959

Adjacent sequences: A201360 A201361 A201362 * A201364 A201365 A201366

Keyword

nonn,hard,more

Author

Michel Lagneau, Nov 30 2011

Extensions

a(4) from Michael S. Branicky, May 12 2023

Status

approved