#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
   unsigned long long sum=0,i,c;
  int  j=k;
    for(i=k;i>=1;i--)
    {
        sum+=i;
    }
    sum*=2;
    sum-=1;
   c=j*(sum-j+1);
    return (c);
}

int main() {
    int k;
    cin >> k;
    long answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}