28237
 13190
 39914
 81367
 8554
 61106
 67448
 39004
 22308
 16054
 71468
 60501
 100
 300
 59632
 90783
 5611
 1000
 69475
 69753
 10
 5
 582
 8
 36961
 5071
 20
 53213
 92775
 28738
 100000
 92280
 37944
 9
 2627
 7
 3

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#include <bits/stdc++.h>
using namespace std;
int n;
long long fCount[100010];
struct Factor {
  int num;
  int times;
};
std::vector<Factor> factors[100010];
int getRemindFactors(int num) {
  int d = 2;
  while (d * d <= num) {
    if (num % d == 0) return num / d;
    if (d == 2)
      d++;
    else
      d += 2;
  }
  return num;
}
void init() {
  Factor newFactor;
  fCount[0] = 0;
  fCount[1] = 0;
  fCount[2] = 0;
  newFactor.num = 2;
  newFactor.times = 1;
  factors[2].push_back(newFactor);
  fCount[3] = 0;
  newFactor.num = 3;
  newFactor.times = 1;
  factors[3].push_back(newFactor);
  fCount[4] = 8;
  newFactor.num = 2;
  newFactor.times = 2;
  factors[4].push_back(newFactor);
}
void render(int num) {
  int r = getRemindFactors(num);
  if (r == num) {
    Factor newFactor;
    newFactor.num = r;
    newFactor.times = 1;
    factors[num].push_back(newFactor);
    fCount[num] = 0;
  } else {
    Factor newFactor;
    bool hasDEqual = false;
    int d = num / r;
    fCount[num] = r * 4;
    if (d != r) {
      fCount[num] = fCount[num] + fCount[r];
      if (r % d != 0) {
        std::vector<Factor>::iterator iFactor;
        for (iFactor = factors[r].begin(); iFactor != factors[r].end();
             iFactor++) {
          newFactor = *iFactor;
          fCount[num] = fCount[num] + (num / newFactor.num) * 4;
          if (newFactor.num == d) {
            newFactor.times++;
            hasDEqual = true;
          }
          factors[num].push_back(newFactor);
        }
      }
    } else {
      if (hasDEqual == false) {
        newFactor.num = d;
        newFactor.times = 2;
        factors[num].push_back(newFactor);
      }
    }
  }
}
int main() {
  scanf("%d", &n);
  init();
  long long sum = 0;
  for (int i = 4; i <= n; i++) {
    render(i);
    sum = sum + fCount[i];
  }
  printf("%I64d\n", sum);
  return 0;
}
