using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace Problem26

{

classProblem26

{

staticvoid Main(string[] args)

{

int num;

double fact1 = 1;

double temp;

double sum = 0;

Console.WriteLine("Enter Number To Display The Sum Of The Following Series i.e. sum of the factorial of series\n Like This 2/1! + 4/3! + 6/5! + 8/7! + 10/9! + . . . +
n/(n-1)!");

num = Convert.ToInt32(Console.ReadLine());

for (int i = 1; i <= num; i++)

{

if (i % 2 != 0)

{

fact1 = 1;

for (int j = 1; j <= i; j++)

{

fact1 = fact1 * j;

}

}

if (i % 2 == 0)

{

temp = i / fact1;

sum = sum + temp;

}

}

Console.WriteLine("\nThe Sum Of The Following Series: " + sum);

Console.ReadKey();

}

}

}

Output: