a(n) = (2*n)^9.

Terms

a(0) =0a(1) =512a(2) =262144a(3) =10077696a(4) =134217728a(5) =1000000000a(6) =5159780352a(7) =20661046784a(8) =68719476736a(9) =198359290368a(10) =512000000000