a(n) = n! - n^2.

Terms

a(0) =1a(1) =0a(2) =-2a(3) =-3a(4) =8a(5) =95a(6) =684a(7) =4991a(8) =40256a(9) =362799a(10) =3628700a(11) =39916679a(12) =479001456a(13) =6227020631a(14) =87178291004