A238011 Numbers k such that (2k)! - k! - 1 is prime.

5, 7, 8, 15, 103, 179, 473, 2054, 3595, 4039

Offset: 1

Author

Rick L. Shepherd, Feb 16 2014

Keywords

• nonn
• hard
• more

Comments

No more terms up to 5000. The first six terms are as previously stated in A118813. All terms found and primes proved by OpenPFGW.

No more terms up to 10000. - Michael S. Branicky, Dec 23 2024

Examples

			5 is a term because (2*5)! - 5! - 1 = 3628679 is prime.
4039 is a term because (2*4039)! - 4039! - 1 is prime (28058 digits).
		

Links

• The OpenPFGW Project, OpenPFGW

Crossrefs

Cf. A118813 (corresponding primes), A237443, A118812.