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

Terms

a(0) =0a(1) =6a(2) =36a(3) =120a(4) =300a(5) =630a(6) =1176a(7) =2016a(8) =3240a(9) =4950a(10) =7260a(11) =10296a(12) =14196a(13) =19110a(14) =25200a(15) =32640a(16) =41616a(17) =52326a(18) =64980a(19) =79800a(20) =97020a(21) =116886a(22) =139656a(23) =165600a(24) =195000a(25) =228150a(26) =265356a(27) =306936a(28) =353220a(29) =404550