a(n) = n! - Sum_{k=0..n-1} k!.

Terms

a(0) =1a(1) =0a(2) =0a(3) =2a(4) =14a(5) =86a(6) =566a(7) =4166a(8) =34406a(9) =316646a(10) =3219686a(11) =35878886a(12) =435046886a(13) =5704064486a(14) =80428314086