a(n) = n^9 - n.

Terms

a(0) =0a(1) =0a(2) =510a(3) =19680a(4) =262140a(5) =1953120a(6) =10077690a(7) =40353600a(8) =134217720a(9) =387420480a(10) =999999990a(11) =2357947680a(12) =5159780340a(13) =10604499360a(14) =20661046770a(15) =38443359360a(16) =68719476720a(17) =118587876480a(18) =198359290350a(19) =322687697760a(20) =511999999980a(21) =794280046560