A099439 Numbers k such that A000295(k) = 2^k-k-1 is prime.

4, 10, 14, 16, 26, 50, 56, 70, 116, 2072, 6250, 13670, 14216, 14626, 396128

Offset: 1

Author

Hugo Pfoertner, Oct 18 2004

Keywords

• nonn
• more
• hard

Comments

The next term is > 400000.

Equals A063791 + 1. - Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 03 2008

Some of the results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019

Examples

			a(1) = 4 because 2^4 - 4 - 1 = 11 is prime.
		

Crossrefs

Cf. A000295 (2^n-n-1), A099440 (primes in A000295), A099441 (2^n-n-1 is a semiprime), A099442 (semiprimes in A000295).

Extensions

a(15) (a PRP) from Karsten Bonath, Jun 07 2018