#include<fstream>   
#include<iostream>   
#define MAX 1000001   
  
using namespace std;   
 
ifstream f("fractii.in");     
ofstream g("fractii.out");     
long long x[MAX],n,s,i,j;    
    
main()   
{     f>>n;    
      f.close();   
      for(i=1;i<=n;i++)     
      x[i]=i-1;     
      for(i=1;i<=n;i++)   
      {     
         for(j=2*i;j<=n;j=j+i)     
         x[j]-=x[i];     
         s+=x[i];     
         }     
      g<<2*s+1;     
      g.close();     
}