a(n) = 4*n^4.

Terms

a(0) =0a(1) =4a(2) =64a(3) =324a(4) =1024a(5) =2500a(6) =5184a(7) =9604a(8) =16384a(9) =26244a(10) =40000a(11) =58564a(12) =82944a(13) =114244a(14) =153664a(15) =202500a(16) =262144a(17) =334084a(18) =419904a(19) =521284a(20) =640000a(21) =777924a(22) =937024a(23) =1119364a(24) =1327104a(25) =1562500a(26) =1827904a(27) =2125764a(28) =2458624a(29) =2829124