a(n) = floor(n! / n^3).

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =0a(5) =3a(6) =14a(7) =78a(8) =497a(9) =3628a(10) =29990a(11) =277200a(12) =2834328a(13) =31770514a(14) =387459072a(15) =5108103000a(16) =72397196844