a(n) = n*(n^2 - 1)*(n+2)*(2*n^5 + 14*n^4 + 49*n^3 + 91*n^2 + 90*n + 18)/324.

Terms

a(0) =0a(1) =0a(2) =92a(3) =1500a(4) =11780a(5) =61880a(6) =249480a(7) =831992a(8) =2403800a(9) =6205760a(10) =14630660a(11) =32006260a(12) =65757692a(13) =128073400a(14) =238223440a(15) =425705840a(16) =734425840a(17) =1228144192a(18) =1997464300a(19) =3168663820a(20) =4914714420a(21) =7468873720a(22) =11141275992a(23) =16338993000