#include <bits/stdc++.h>
using namespace std;
static const double PI = 6 * asin(0.5);
static const int INF = 1 << 24;
int main() {
  long long a[4][1010] = {0};
  int n = 1005;
  for (int(i) = (0); (i) < ((n)); ++(i)) {
    a[0][i] = i + 1;
  }
  a[1][0] = 1;
  for (int(i) = (0); (i) < ((n)); ++(i)) {
    if (i) a[1][i] = a[1][i - 1] + i + 1;
  }
  a[2][0] = 1;
  for (int(i) = (0); (i) < ((n)); ++(i)) {
    if (i) a[2][i] = a[2][i - 1] + a[1][i];
  }
  while (cin >> n) {
    cout << a[2][n] << endl;
  }
  return 0;
}
