Catalan numbers

using System;
class CatalanNumbers
{
    static void Main()
    {
        Console.Write("Enter n (1<n<100) : ");
        decimal n = decimal.Parse(Console.ReadLine());
        decimal cn =1;
        if (n==0)
        {
            Console.WriteLine("1");
        }
        else if (1<n&&n<100)
        {
            for (int k = 2; k <= n; k++)
            {
                cn*=(n/k+1);

            }
            Console.WriteLine("Cn = {0:F0}", cn);
        }
        else
        {
            Console.WriteLine("Invalid input!");
        }
    }
}