#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <cmath>
#include <climits>
#include <algorithm>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <cassert>
#include <vector>
#define all(x) x.begin() , x.end()
#define fi first
#define se second
#define pb push_back
#define umax( x , y ) x = max( x , (y) )
#define umin( x , y ) x = min( x , (y) )
#define For( i , a ) for(int i=1;i<=a;i++)
#define ort (b+s)/2
#define y2 asrwjaelkf
#define y1 asseopirwjaelkf
#define set multiset

using namespace std;

inline int read() {
    int res = 0 ;int neg ;
    while(true){char ch = getchar();if(ch>='0' && ch<='9' || ch=='-'){if(ch=='-') neg = -1;else neg = 1 , res = ch-'0';break;} }
    while(true){char ch = getchar();if(ch>='0' && ch<='9') res*=10 , res+=ch-'0';else break;}
    return res*neg;
}


typedef long long Lint;
typedef double db;
typedef pair<int,int> ii;
typedef pair<db,db> dd;
typedef pair<db,int> di;
typedef pair<ii,int> iii;
typedef pair<ii,ii> i4;

const int maxn = 1000020;
const int maxm = 10000020;
const int MOd = 1e9 + 7;
const int K = 300;

Lint a, b;

int main() {

    //freopen("asd.in","r",stdin);
    //freopen("out.txt","w",stdout);

    scanf("%lld",&a);

    Lint ans = a;

    Lint b = a*(a-1)/2;

    ans += ( a * b + a*(a-1)/2 ) * 2;

    cout << ans << endl;



    return 0;
}