a(n) = n! + (n-1)! + n-2.

Terms

a(0) =1a(1) =3a(2) =9a(3) =32a(4) =147a(5) =844a(6) =5765a(7) =45366a(8) =403207a(9) =3991688a(10) =43545609a(11) =518918410a(12) =6706022411a(13) =93405312012