a(n) = n^4*(n+1)^2/2.

Terms

a(0) =0a(1) =2a(2) =72a(3) =648a(4) =3200a(5) =11250a(6) =31752a(7) =76832a(8) =165888a(9) =328050a(10) =605000a(11) =1054152a(12) =1752192a(13) =2798978a(14) =4321800a(15) =6480000a(16) =9469952a(17) =13530402a(18) =18948168a(19) =26064200a(20) =35280000a(21) =47064402a(22) =61960712a(23) =80594208a(24) =103680000a(25) =132031250a(26) =166567752a(27) =208324872