a(n) = (2*n+1)*(n+1)*(2*n^2+3*n-1).

Terms

a(0) =-1a(1) =24a(2) =195a(3) =728a(4) =1935a(5) =4224a(6) =8099a(7) =14160a(8) =23103a(9) =35720a(10) =52899a(11) =75624a(12) =104975a(13) =142128a(14) =188355a(15) =245024a(16) =313599a(17) =395640a(18) =492803a(19) =606840a(20) =739599a(21) =893024a(22) =1069155a(23) =1270128a(24) =1498175a(25) =1755624a(26) =2044899a(27) =2368520a(28) =2729103a(29) =3129360