#include <stdio.h>
#include<math.h>
int tot,n,i;
int sub(int nr)
{
    int f,p,cnr,sum;
    f=2;
    sum=nr;
    while(nr!=1)
    {
        p=0;
        while(nr%f==0)
        {
            p++;
            nr=nr/f;
        }
    if(p!=0)
        sum=sum*(f-1)/f;
    f++;
    }
    return sum;
}
using namespace std;

int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    for(i=2;i<=n;i++)
     {

        tot=tot+sub(i);
     }
    printf("%d",tot*2+1);
}