a(n) = (3*n)!/(2*n)!.

A064352

a(n) = (3*n)!/(2*n)!.

Terms

    a(0) =1a(1) =3a(2) =30a(3) =504a(4) =11880a(5) =360360a(6) =13366080a(7) =586051200a(8) =29654190720

External references