a(n) = n! - n^7.

Terms

a(0) =1a(1) =0a(2) =-126a(3) =-2181a(4) =-16360a(5) =-78005a(6) =-279216a(7) =-818503a(8) =-2056832a(9) =-4420089a(10) =-6371200a(11) =20429629a(12) =443169792a(13) =6164272283a(14) =87072877696