a(n) = (3*n)^4.

Terms

a(0) =0a(1) =81a(2) =1296a(3) =6561a(4) =20736a(5) =50625a(6) =104976a(7) =194481a(8) =331776a(9) =531441a(10) =810000a(11) =1185921a(12) =1679616a(13) =2313441a(14) =3111696a(15) =4100625a(16) =5308416a(17) =6765201a(18) =8503056a(19) =10556001a(20) =12960000a(21) =15752961a(22) =18974736a(23) =22667121a(24) =26873856a(25) =31640625a(26) =37015056a(27) =43046721a(28) =49787136a(29) =57289761