#include<fstream.h>
#include<math.h>
long long n,nr,i,x,d,totient,k;
fstream f("fractii.in",ios::in); fstream g("fractii.out",ios::out);
void main()
{  f>>n;
   nr=0;
   for(i=2;i<=n;i++)
    { x=i;
      d=2;
      totient=1;
      while (x!=1)
	{  k=0;
	   while (x%d==0) { k++;
			    x=x/d;
			  }
	   if (k>0) totient=totient*(d-1)*pow(d,k-1);
	   d++;
	}
      nr+=totient;
    }
g<<nr*2+1;
g.close();
}