#include <fstream>

using namespace std;

ifstream cin ("fractii.in");
ofstream cout ("fractii.out");

int main()
{
    int a;
    cin>>a;
    int nr=1;
    for (int i=2; i<=a; i++)
    {
        int d=2;
        int ci=i;
        int ind=1;
        while (ci!=1)
        {
            int p=0;
            int putere=1;
            while (ci%d==0)
            {
                ci/=d;
                p++;
                putere*=d;
            }
            if (p>0)
            {
                ind*=(d-1)*(putere/d);
            }
            d++;
        }
        nr+=ind*2;
    }
    cout<<nr;
    return 0;
}