a(n) = ((n-1)! * (n+1)!) / n.A179442a(n) = ((n-1)! * (n+1)!) / n.Terms a(0) =2a(1) =3a(2) =16a(3) =180a(4) =3456a(5) =100800a(6) =4147200a(7) =228614400a(8) =16257024000External referencesoeis: A179442