a(n) = n^2 * (n+1)^2 * (n^2+n+1) / 12.

Terms

a(0) =0a(1) =1a(2) =21a(3) =156a(4) =700a(5) =2325a(6) =6321a(7) =14896a(8) =31536a(9) =61425a(10) =111925a(11) =193116a(12) =318396a(13) =505141a(14) =775425a(15) =1156800a(16) =1683136a(17) =2395521a(18) =3343221a(19) =4584700a(20) =6188700a(21) =8235381a(22) =10817521a(23) =14041776a(24) =18030000a(25) =22920625a(26) =28870101a(27) =36054396a(28) =44670556a(29) =54938325