#include<bits/stdc++.h>
using namespace std;
int he(int n){
	int r,c=0;
	if(n==1) r=1;
	else{
		r=he(n-1)+n-1;
	}
	return r;
}
int n,s=0;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		s=s+he(i);
	}
	cout<<s;

	return 0;
}

/**************************************************************
	Problem: 1145
	User: zhuanghaoxiang
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/