a(n) = n! - prime(n).

Terms

a(0) =-1a(1) =-1a(2) =1a(3) =17a(4) =109a(5) =707a(6) =5023a(7) =40301a(8) =362857a(9) =3628771a(10) =39916769a(11) =479001563a(12) =6227020759a(13) =87178291157