A049614(n)/A131685(n).

Terms

a(0) =1a(1) =1a(2) =1a(3) =4a(4) =4a(5) =24a(6) =24a(7) =192a(8) =1728a(9) =17280a(10) =17280a(11) =207360a(12) =207360a(13) =414720a(14) =6220800a(15) =99532800a(16) =696729600a(17) =12541132800a(18) =12541132800a(19) =250822656000