a(n) = n^3*7^n.

Terms

a(0) =0a(1) =7a(2) =392a(3) =9261a(4) =153664a(5) =2100875a(6) =25412184a(7) =282475249a(8) =2951578112a(9) =29417779503a(10) =282475249000