Можно и без него, конечно:
Код:
#include <iostream>
#include <cmath>
unsigned __int64 fact(unsigned __int64 n)
{
if ((n == 1) || (n == 0))
{
return 1;
}
else
{
return n * fact(n - 1);
}
}
int main()
{
unsigned __int64 n;
do
{
std::cout << "Enter n (n >= 1 and n = 1 (mod 2)):\r\n\";
std::cin >> n;
} while ((n < 1) || (n % 2 == 0));
std::cout << "Enter x:\r\n";
double x;
std::cin >> x;
double summ = 0.0;
for (unsigned __int64 i = 1; i <= n; i += 2)
{
summ += pow(x, (double)i) / fact(i);
}
std::cout << "Result: " << summ << "\r\n\r\n";
return 0;
}