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

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

Offset

1,1

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.

Links

Table of n, a(n) for n=1..10.

The OpenPFGW Project, OpenPFGW

Example

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).

Crossrefs

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

Sequence in context: A288151 A242408 A171952 * A140237 A032683 A182005

Adjacent sequences: A238008 A238009 A238010 * A238012 A238013 A238014

Keyword

nonn,hard,more

Author

Rick L. Shepherd, Feb 16 2014

Status

approved