#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout ("fractii.out");
int phi(int n)
{int r = n , d = 2;
    while(n > 1)
    {
        if(n % d == 0)
        {
            r = r / d * (d - 1);
            while(n % d == 0)
                n /= d;
        }
        d ++;
        if(d * d > n)
            d = n;
    }
    return r;
}


unsigned long long int s;
int main()
{unsigned int n,i;
fin>>n;
for(i=2;i<=n;i++)
{s=s+phi(i);

}
s=s*2+1;
fout<<s;
fin.close();
fout.close();
    return 0;
}