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

Terms

a(0) =2a(1) =3a(2) =5a(3) =10a(4) =29a(5) =126a(6) =727a(7) =5048a(8) =40329a(9) =362890a(10) =3628811a(11) =39916812a(12) =479001613a(13) =6227020814a(14) =87178291215