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

C# Program to printsum of the factorial of odd series multiply with x where power of x is square of corresponding
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 .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.RdLine());
Console.Write("\n\t\tEnter ending point : ");
n = Convert.ToInt32(Console.RdLine());
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);
}
}