#include <iostream>

using namespace std;
int fact(int n) {
	if (n == 0) return 1;
	return n * fact(n - 1);

}
double sum(int n) {
	/*int s = 0;
	while(n>0){

		s += (2.0 * n )/ ((2.0 * n - 1) * fact(2.0 * n + 2.0));
		n--;

	}*/
	if (n == 1) return (2/(3*fact(4)));
	return ((2*n)/(((2 * n) - 1) * fact((2 * n) + 2)))+ sum(n-1);
	//return s;
}
int main(){
	cout<<fact(3)<<endl;
	cout << (double)sum(1)<<endl;
	cout << (double)sum(2);

	return 0;
}