a(n) = n! / A284567(n).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =36a(7) =36a(8) =576a(9) =576a(10) =57600a(11) =57600a(12) =57600a(13) =57600a(14) =2822400a(15) =25401600a(16) =25401600a(17) =25401600a(18) =8230118400a(19) =8230118400