#include <stdio.h>
FILE *f,*g;   
long n,nd,contor,nr,d;
int main() {   
f=fopen("fractii.in" , "r");   
g=fopen("fractii.out" , "w");   
fscanf(f, "%ld" , &n);   
fclose(f);   
contor=n;
for(nr=n;nr>=3;nr--){nd=0;
		     for(d=2;d<=n/2;d++)if(nr%d==0)nd++;
                     contor=contor+nr-1-nd;}
fprintf(g,"%ld", contor*2);
fclose(g);   
return 0;   
}