a(n) = (2*n + 1)!/(n + 1).A110468a(n) = (2*n + 1)!/(n + 1).Terms a(0) =1a(1) =3a(2) =40a(3) =1260a(4) =72576a(5) =6652800a(6) =889574400a(7) =163459296000External referencesoeis: A110468