#include <iostream>
#include <fstream>
using namespace std;
int main(){
ifstream f("fractii.in");
ofstream g("fractii.out");
long int n,d,e,nr;
f>>n;
nr=2*n-1;
for(d=2;d<n-1;d++){
    for(e=d+1;e<n;e++) if(e%d) nr+=2;
}
g<<nr;
return 0;
}