a(n) = (7*n + 4)^6.

Terms

a(0) =4096a(1) =1771561a(2) =34012224a(3) =244140625a(4) =1073741824a(5) =3518743761a(6) =9474296896a(7) =22164361129a(8) =46656000000a(9) =90458382169a(10) =164206490176a(11) =282429536481a(12) =464404086784a(13) =735091890625