a(n) = n! + n.

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =28a(5) =125a(6) =726a(7) =5047a(8) =40328a(9) =362889a(10) =3628810a(11) =39916811a(12) =479001612a(13) =6227020813a(14) =87178291214