a(n) = n! + n^2.

Terms

a(0) =1a(1) =2a(2) =6a(3) =15a(4) =40a(5) =145a(6) =756a(7) =5089a(8) =40384a(9) =362961a(10) =3628900a(11) =39916921a(12) =479001744a(13) =6227020969a(14) =87178291396