a(n) = n^7*(n + 1)/2.

Terms

a(0) =0a(1) =1a(2) =192a(3) =4374a(4) =40960a(5) =234375a(6) =979776a(7) =3294172a(8) =9437184a(9) =23914845a(10) =55000000a(11) =116923026a(12) =232906752a(13) =439239619a(14) =790601280a(15) =1366875000a(16) =2281701376a(17) =3693048057a(18) =5816090304a(19) =8938717390a(20) =13440000000a(21) =19811973951a(22) =28685115712a(23) =40857905364a(24) =57330892800