a(n) = (n-1)! * Product_{k=1..n-2} (n-k)!.

A152653

a(n) = (n-1)! * Product_{k=1..n-2} (n-k)!.

Terms

    a(0) =1a(1) =1a(2) =4a(3) =72a(4) =6912a(5) =4147200a(6) =17915904000

External references