OFFSET
1,3
EXAMPLE
a(9) = 8 because 8*9!! + 1 = 8*945 + 1 = 7561 is prime.
MATHEMATICA
Table[k = 0; While[!PrimeQ[k*n!! +1], k++]; k, {n, 85}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Dec 19 2011
STATUS
approved