include<bits/stdc++.h>

using namespace std; int main () { int n , sum = 0 ,fact = 1; cin >> n; for ( int i = 1; i <= n ; ++ i) { fact *= i; sum += fact;

}
cout << sum << endl;
return 0;

}

#include<bits/stdc++.h>
using namespace std;
int main ()
{
    int n , sum = 0 ,fact = 1;
    cin >> n;
    for ( int i = 1; i <= n ; ++ i)
    {
        fact *= i;
        sum += fact;

    }
    cout << sum << endl;
    return 0;
}