a(n) = n^6*(n+1)^2/2.

Terms

a(0) =0a(1) =2a(2) =288a(3) =5832a(4) =51200a(5) =281250a(6) =1143072a(7) =3764768a(8) =10616832a(9) =26572050a(10) =60500000a(11) =127552392a(12) =252315648a(13) =473027282a(14) =847072800a(15) =1458000000a(16) =2424307712a(17) =3910286178a(18) =6139206432a(19) =9409176200a(20) =14112000000a(21) =20755401282a(22) =29988984608