#include<bits/stdc++.h>
using namespace std;
int a[200],n,c=0,d=0;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		c=c+i;
		d=d+c;
	}
	cout<<d;

	return 0;
}

/**************************************************************
	Problem: 1148
	User: zhuanghaoxiang
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/