a(n) = n^2*(n^2 - 1)^2/2.

Terms

a(0) =0a(1) =18a(2) =288a(3) =1800a(4) =7200a(5) =22050a(6) =56448a(7) =127008a(8) =259200a(9) =490050a(10) =871200a(11) =1472328a(12) =2384928a(13) =3726450a(14) =5644800a(15) =8323200a(16) =11985408a(17) =16901298a(18) =23392800a(19) =31840200a(20) =42688800a(21) =56455938a(22) =73738368a(23) =95220000a(24) =121680000a(25) =154001250a(26) =193179168a(27) =240330888a(28) =296704800a(29) =363690450