a(n) = -(1/120)*n*(n - 3)*(n - 6)*(n^2 - 21*n + 8).

Terms

a(0) =0a(1) =1a(2) =2a(3) =0a(4) =-4a(5) =-6a(6) =0a(7) =21a(8) =64a(9) =135a(10) =238a(11) =374a(12) =540a(13) =728a(14) =924a(15) =1107a(16) =1248a(17) =1309a(18) =1242a(19) =988a(20) =476a(21) =-378a(22) =-1672a(23) =-3519a(24) =-6048a(25) =-9405a(26) =-13754a(27) =-19278a(28) =-26180a(29) =-34684