a(n) = 8*(n-1)*(n-2)*(n-3)*(6*n^2-37*n+60).

Terms

a(0) =0a(1) =0a(2) =0a(3) =384a(4) =4800a(5) =25920a(6) =91200a(7) =248640a(8) =572544a(9) =1169280a(10) =2183040a(11) =3801600a(12) =6262080a(13) =9856704a(14) =14938560a(15) =21927360a(16) =31315200a(17) =43672320a(18) =59652864a(19) =80000640a(20) =105554880a(21) =137256000a(22) =176151360a(23) =223401024a(24) =280283520a(25) =348201600a(26) =428688000a(27) =523411200