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

Terms

a(0) =0a(1) =1a(2) =4a(3) =17a(4) =86a(5) =517a(6) =3620a(7) =28961a(8) =260650a(9) =2606501a(10) =28671512a(11) =344058145a(12) =4472755886a(13) =62618582405a(14) =939278736076