OFFSET
1,2
COMMENTS
No further terms up to n=20000. The sequence a[n]=Sum(n!/k!),k=0..n is A000522.
FORMULA
n is an index of the sequence a[n]=Sum(n!/k!),k=0..n such that a[n] is prime.
EXAMPLE
For n=2, a[2]=5 which is a prime.
PROG
(PARI) a=1; for(n=1, 20000, a=n*a+1; if(ispseudoprime(a, 0), print("n="n)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Mike Oakes, Oct 12 2009
STATUS
approved