#include <iostream>
#include <fstream>
using namespace std;

int cauta( int n, int *p) {
  int i,j, nr = 1;
  for(i = 2; i <= n/2; i++)
    if(n % i == 0)
      for (j = i  ; j <= n; j = j + i){
        if(p[j] == 0){
        nr++;
        p[j] = 1;
        }
      }

  if(p[n] == 0){
    nr++;
    p[n] = 1;
  }
  return n - nr;
}


int main()
{
    ifstream in;
    in.open("fractii.in");
    ofstream out;
    out.open("fractii.out");
    int nr,suma;
    in >> nr;
    suma = nr+nr-1;
    int *p = new int[nr+1];
    for (int i = 2 ; i <= nr ; i++){
        suma += cauta (i,p)*2;
    }
    out << suma << endl;
    return 0;
}