OFFSET
1,1
COMMENTS
a(4) = 125411328001 and the 65-digit a(5) have been certified prime with Primo. Any additional terms are too big to include here. a(3) = 13 and a(4) have twin primes, 11 and 125411327999 (also certified prime with Primo). No other primes of the form 0!*1!*2!*...*n! - 1 exist for n < 108.
REFERENCES
Ryser, H. J. Combinatorial Mathematics. Buffalo, NY: Math. Assoc. Amer., p. 53, 1963.
LINKS
FORMULA
a(k) = 1 + 0!*1!*2!*...*A073827(k)!.
EXAMPLE
PROG
(PARI) pr=1; for(n=0, 115, pr=pr*n!; if(isprime(pr+1), print1(pr+1, ", ")))
CROSSREFS
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Aug 16 2002
STATUS
approved