a(n) = (n+1)*binomial(n+1,7).

Terms

a(0) =7a(1) =64a(2) =324a(3) =1200a(4) =3630a(5) =9504a(6) =22308a(7) =48048a(8) =96525a(9) =183040a(10) =330616a(11) =572832a(12) =957372a(13) =1550400a(14) =2441880a(15) =3751968a(16) =5638611a(17) =8306496a(18) =12017500a(19) =17102800a(20) =23976810a(21) =33153120a(22) =45262620a(23) =61074000a(24) =81516825a(25) =107707392a(26) =140977584a(27) =182906944a(28) =235358200a(29) =300516480