Denominator of n^(n-2)/n!.

Terms

a(0) =1a(1) =2a(2) =2a(3) =3a(4) =24a(5) =5a(6) =720a(7) =315a(8) =4480a(9) =567a(10) =3628800a(11) =1925a(12) =479001600a(13) =868725a(14) =14350336a(15) =638512875a(17) =14889875a(19) =14849255421