a(n) = (9*n + 4)^6.

Terms

a(0) =4096a(1) =4826809a(2) =113379904a(3) =887503681a(4) =4096000000a(5) =13841287201a(6) =38068692544a(7) =90458382169a(8) =192699928576a(9) =377149515625a(10) =689869781056