a(n) = n*(n-1)*A056219(n+1).

Terms

a(0) =4a(1) =24a(2) =60a(3) =120a(4) =270a(5) =546a(6) =840a(7) =1368a(8) =2250a(9) =3740a(10) =5544a(11) =7956a(12) =11102a(13) =16380a(14) =23520a(15) =33184a(16) =44676a(17) =59850a(18) =79420a(19) =106260a(20) =141834a(21) =189244a(22) =245088a(23) =314400a(24) =401050a(25) =511758a(26) =648648a(27) =824992a(28) =1044000a(29) =1315020