%N Numbers n such that Sum(n!/k!),k=0..n is prime.
%C No further terms up to n=20000. The sequence a[n]=Sum(n!/k!),k=0..n is A000522.
%F n is an index of the sequence a[n]=Sum(n!/k!),k=0..n such that a[n] is prime.
%e For n=2, a=5 which is a prime.
%o (PARI) a=1;for(n=1,20000,a=n*a+1;if(ispseudoprime(a,0),print("n="n)));
%Y Cf. A000522 (corresponding sequence).
%A _Mike Oakes_, Oct 12 2009