#include <stdio.h>
#include <stdlib.h>

int calculare_ie(int n)
{
    int a=n,d=2;
    while(n>1)
    {
        if(n%d==0)
        {
            a/=d;
            a*=d-1;
        }
        while(n%d==0)
        {
            n/=d;
        }
        if(d==2)
        {
            d++;
        }
        else
        {
            d+=2;
        }

    }
    return a;
}

int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    int n,s=0,i;
    scanf("%d",&n);
    for(i=2;i<=n;i++)
    {
        s+=calculare_ie(i);
    }
    s*=2;
    s+=1;
    printf("%d",s);
    return 0;
}