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

Terms

a(0) =0a(1) =1a(2) =12a(3) =60a(4) =200a(5) =525a(6) =1176a(7) =2352a(8) =4320a(9) =7425a(10) =12100a(11) =18876a(12) =28392a(13) =41405a(14) =58800a(15) =81600a(16) =110976a(17) =148257a(18) =194940a(19) =252700a(20) =323400a(21) =409101a(22) =512072a(23) =634800a(24) =780000a(25) =950625a(26) =1149876a(27) =1381212a(28) =1648360a(29) =1955325