用C表示组合数C(2n,n) = (2n)!/ (n!× n!)C(2n,n - 1) = (2n)!/ [ (n-1)!× (n + 1)!](2n)!/ [n!× (n + 1)!] = C(2n,n) - C(2n,n - 1)C(2n,n) 和 C(2n,n - 1) 都是整数∴(2n)!/ [n!× (n + 1)!]是整数...
