OFFSET
1,1
COMMENTS
Let S(n) = Sum_{i=0,..n-1} (i!)^2. Note that 6 divides S(n) for n>1. For prime p=20879, p divides S(p-1). Hence p divides S(n) for all n >= p-1 and all prime values of S(n)/6 are for n < p-1. These n yield provable primes for n <= 93. No other n < 4000.
No other n < 8000. [T. D. Noe, Jul 31 2008]
MATHEMATICA
f2=1; s=2; Do[f2=f2*n*n; s=s+f2; If[PrimeQ[s/6], Print[{n, s/6}]], {n, 2, 100}]
CROSSREFS
KEYWORD
fini,nonn
AUTHOR
T. D. Noe, Dec 18 2004
STATUS
approved