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

Terms

a(0) =0a(1) =1296a(2) =20736a(3) =104976a(4) =331776a(5) =810000a(6) =1679616a(7) =3111696a(8) =5308416a(9) =8503056a(10) =12960000a(11) =18974736a(12) =26873856a(13) =37015056a(14) =49787136a(15) =65610000a(16) =84934656a(17) =108243216a(18) =136048896a(19) =168896016a(20) =207360000a(21) =252047376a(22) =303595776a(23) =362673936a(24) =429981696a(25) =506250000a(26) =592240896a(27) =688747536