The OEIS is supported by the many generous donors to the OEIS Foundation.
%I #7 Oct 02 2016 17:49:46
%S 0,5,35,577,14399,518401,25401599,1625702401,131681894399,
%T 13168189440001,1593350922239999,229442532802560001,
%U 38775788043632639999,7600054456551997440001,1710012252724199423999999,437763136697395052544000001,126513546505547170185215999999
%N a(n) = n!^2 + (-1)^n.
%C p = 2*n+1 is prime iff it divides a(n) (Wilson's theorem) for instance let n=5, p =11 : a(5) = 14399 = 11*1309, so 11 is prime.
%F a(n) = n^2*(a(n-1)-(-1)^(n-1))+(-1)^n.
%e a(5) = 14399 because 14399=(5!)^2+(-1)^5.
%o (PARI) a(n) = n!^2+(-1)^n; \\ _Michel Marcus_, Oct 02 2016
%K easy,nonn
%O 1,2
%A Serge Boisse (serge.boisse(AT)aviation-civile.gouv.fr), Dec 02 2003
%E Offset corrected and edited by _Michel Marcus_, Oct 02 2016