#include<fstream>
#include<iostream>
#define MAX 1000001

using namespace std;

ifstream f("fractii.in");  
ofstream g("fractii.out");  

long long a[MAX],n,s,i,j; 
 
main()
{     f>>n; 
      f.close();
      for(i=1;i<=n;i++)  
      a[i]=i-1;  
      for(i=1;i<=n;i++)
      {  
         for(j=2*i;j<=n;j=j+i)  
         a[j]-=a[i];  
         s+=a[i];  
         }  
      g<<2*s+1;  
      g.close();  
}