a(n) = 28*(n+1)*binomial(n+3,8)/3.

Terms

a(0) =56a(1) =588a(2) =3360a(3) =13860a(4) =46200a(5) =132132a(6) =336336a(7) =780780a(8) =1681680a(9) =3403400a(10) =6534528a(11) =11992344a(12) =21162960a(13) =36085560a(14) =59690400a(15) =96101544a(16) =151016712a(17) =232178100a(18) =349949600a(19) =518017500a(20) =754233480a(21) =1081620540a(22) =1529564400a(23) =2135214900a(24) =2945124000a(25) =4017149136a(26) =5422652928