/******************************************************************************

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#include <bits/stdc++.h>
using namespace std;
int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    
    
    
    long long n,v[1000005];
    f>>n;
    for (int i=2; i<=n; i++)
    v[i]=i;
    for (int i=2;i<=n;i++) {
    if (v[i]==i) {
        v[i]--;
        
        for (int j=i*2;j<=n;j+=i) {
            
            v[j]=v[j]/i*(i-1);
            
        }
        
        
        
    }
    
    
    }
    long long sol=0;
    for (int i=2;i<=n;i++) {
        
        sol+=v[i]*2;
    }
        sol+=1;
        g<<sol;
    
    
    
    
    
    return 0;
}