/********************
    Created by Sburly
********************/
#include <fstream>
#include <vector>

using namespace std;

vector<int> v;

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

    long int n;
    f >> n;
    bool prim[n+1];
    long int sol = 0;


    for (long int i = 2; i <= n; i++)
        prim[i] = true;
    for (long int i = 2; i <= n; i++)
    {
        if (prim[i])
        {
            v.push_back(i);
            for (long int j = i+i; j <= n; j += i)
                prim[j] = false;
            sol +=i-1;
        }
        else
        {
            float p = i;
            for(long int j = 0; j < v.size();j++)
            {
                if(i % v[j] == 0)
                p *= 1 - (float)1/v[j];
            }
            sol+=p;
        }
    }
    g << sol*2+1;

    return 0;
}