a(n) = (8*n + 6)^6.

Terms

a(0) =46656a(1) =7529536a(2) =113379904a(3) =729000000a(4) =3010936384a(5) =9474296896a(6) =24794911296a(7) =56800235584a(8) =117649000000a(9) =225199600704a(10) =404567235136a(11) =689869781056