#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <functional>
#include <iostream>
#include <map>
#include <set>
using namespace std;
typedef pair<int,int> P;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-7
#define INF 2000000000
int main()
{
	int n;
	int dp[4001];
	dp[0]=1;
	for(int i=0;i<4000;i++)
	{
		dp[i+1]=dp[i]+(i+2)*(i+3)/2;
	}
	while(cin >> n)
	{
		cout << dp[n] << endl;
	}
	return 0;
}