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

Terms

a(0) =0a(1) =2a(2) =12a(3) =72a(4) =480a(5) =3600a(6) =30240a(7) =282240a(8) =2903040a(9) =32659200a(10) =399168000a(11) =5269017600a(12) =74724249600