#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");

int euler(int n)
{
    int x=1;
    for (int i=2;i<=n-1;i++)
    {
        if (n%i!=0) x++;
    }
return x;

}
int main()
{
    int a;
    int b[500000];
    fin>>a;
    b[1]=1;
    for (int j=2;j<=a;j++)
    {
        b[j]=b[j-1]+2*euler(j);
    }
    fout<<b[a];
    return 0;
}