A238011 - OEIS

%I #5 Feb 17 2014 01:59:23

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

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

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

%H The OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">OpenPFGW</a>

%e 5 is a term because (2*5)! - 5! - 1 = 3628679 is prime.

%e 4039 is a term because (2*4039)! - 4039! - 1 is prime (28058 digits).

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

%K nonn,hard,more

%O 1,1

%A _Rick L. Shepherd_, Feb 16 2014