#include <iostream>
#include<fstream>



using namespace std;

ifstream f;
ofstream g;

int main()
{
    long i,j,n;

long t[1000002],k=0;

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

f>>n;

k=0;
for(i=2;i<=n;i++)
        {
        t[j]=i-1;
        for(j=i+i;j<=n;j+=i)
            t[j]=t;
        k+=t;
        }

g<<k*2+1;
return 0;
}