C# Program to print sum of the factorial of odd series multiply with x where power of x is square of corresponding number

C# Program to print sum of the factorial of odd series multiply with x where power of x is square of corresponding number

Program Statement:

Write a program to display the sum of the following series i.e. sum of the factorial of odd series multiply with x where power of x is square of corresponding number.

X1*1! + X9*3! + X25*5! + X49*7! + X81*9! + . . . + Xn2*n!

Solution:

 class _power
   {
       long n, f, x, sum = 0;
       public long power(long a, long b)
       {
           long res = 1;
           for (int i = 1; i <= b; i++)
               res = res * a;
           return res;
       }
       public void cal()
       {
           Console.WriteLine("\n\t\tSeries X^1*1! + X^9*3 +...+X^n2*n! \n");
           Console.Write("\n\t\tEnter value of x : ");
           x = Convert.ToInt32(Console.ReadLine());
           Console.Write("\n\t\tEnter ending point : ");
           n = Convert.ToInt32(Console.ReadLine());
           for (int i = 1; i <= n; i++)
           {
               if (i % 2 != 0)
               {
                   f = 1;
                   for (int j = i; j >= 1; j--)
                       f = f * j;
                   sum = sum + ((power(x, i * i)) * f);
               }
           }
           Console.WriteLine("\n\t\tResult = {0}\n", sum);
       }
   }