a(n) = 5*n! + 1.

Terms

a(0) =6a(1) =6a(2) =11a(3) =31a(4) =121a(5) =601a(6) =3601a(7) =25201a(8) =201601a(9) =1814401a(10) =18144001a(11) =199584001a(12) =2395008001a(13) =31135104001a(14) =435891456001