a(n) = Product_{i=1..n} floor(3*i/2).

Terms

a(0) =1a(1) =3a(2) =12a(3) =72a(4) =504a(5) =4536a(6) =45360a(7) =544320a(8) =7076160a(9) =106142400a(10) =1698278400a(11) =30569011200a(12) =580811212800