#include<fstream.h>
ifstream fin("fractii.in");
ofstream fout("fractii.out");
long n,i,k,sw=1,s=1,j,p,d,putere,putere2;
int main()
{fin>>n;
 for(i=2;i<=n;i++)
  { j=i;p=1;d=2;
    while(j!=1)
    { sw=1;
      for(k=2;k<=d/2;k++)if(d%k==0){sw=0;break;}
      //algoritm numar prim pt 'd';
      if(sw==1)
       {    putere=0;
            putere2=1;
          while(j%d==0)
          { putere++;
	    putere2*=d;
	    j=j/d;
          }
           if(putere!=0)p=p*(d-1)*(putere2/d);
        }
      if(d==2)d++;else d+=2;
    }
    s+=p*2;
  }
fout<<s;
fin.close();
fout.close();
return 0;
}