#27505: _CPP
#include <iostream>
using namespace std;
int main(){
int n;
while (cin >> n){
cout << (n*n*n+5*n+6)/6 <<endl;
}
}
#include <iostream>
using namespace std;
int main(){
int n;
while (cin >> n){
cout << (n*n*n+5*n+6)/6 <<endl;
}
}