a(n+1) = (n-1)*a(n) + n*n!.

Terms

a(0) =1a(1) =5a(2) =28a(3) =180a(4) =1320a(5) =10920a(6) =100800a(7) =1028160a(8) =11491200a(9) =139708800a(10) =1836172800a(11) =25945920000a(12) =392302310400