a(n) = 4*(n^1 + 1!)*(n^2 + 2!)*(n^3 + 3!)*(n^4 + 4!)/4!.

Terms

a(0) =48a(1) =175a(2) =1680a(3) =25410a(4) =294000a(5) =2295513a(6) =12991440a(7) =57550100a(8) =211281840a(9) =669529875a(10) =1885734928a(11) =4823347830a(12) =11387316720a(13) =25126129245a(14) =52326450000a(15) =103659864168a(16) =196585724720a(17) =358766207415a(18) =632810010000