OFFSET
1,2
COMMENTS
a(1)-a(11) were found by Earls (2003-2004).
The corresponding primes are 2, 5, 241, 110881, 3256459844769331201, ... .
LINKS
Jason Earls, Marching Primes: !N x N! + 1, Journal of Recreational Mathematics, Vol. 32, No. 2 (2003-2004), pp. 123-124.
MATHEMATICA
Select[Range[300], PrimeQ[#! * Sum[k!, {k, 0, #-1}] + 1] &]
PROG
(PARI) is(k) = isprime(k! * sum(i = 0, k-1, i!) + 1);
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Oct 01 2024
EXTENSIONS
a(14)-a(16) from Michael S. Branicky, Oct 03 2024
STATUS
approved