#include <iostream>
#include<fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");

int CMMDC(int a,int b)
{
    int c;
    while(b)
    {
        c=a%b;
        a=b;
        b=c;
    }
    return a;
}

int main()
{
    int N,i,j,nr=1;
    bool v[1000000];
    f>>N;
    for(i=1;i<=N;i++)
   {
       v[i]=1;
   }
   for(i=2;i<=N;i++)
    {
        if(v[i]==1)
            {
                nr=nr+(2*i)-2;
                for(j=2*i;j<=N;j+=i)
                {v[j]=0;}
            }
        else
            {
                nr+=2;
                for(j=2;j<i;j++)
                    {
                        if(CMMDC(i,j)==1)
                            {
                                nr+=2;
                            }
                    }
            }
    }
    g<<nr;
}