a(0) = 1; a(n) = (n-1)*a(n-1) + n.

Terms

a(0) =1a(1) =1a(2) =3a(3) =9a(4) =31a(5) =129a(6) =651a(7) =3913a(8) =27399a(9) =219201a(10) =1972819a(11) =19728201a(12) =217010223a(13) =2604122689a(14) =33853594971a(15) =473950329609