#include <iostream>
#include<cstdio>
FILE * f=fopen("fractii.in","r");
FILE * g=fopen("fractii.out","w");
using namespace std;
long long int n;

long long int phi[1000000];
int main()
{ long long int t=0,i,j;

fscanf(f,"%lld",&n);

for ( i = 1; i <= n; ++i)
    phi[i] = i-1;
for ( i = 2; i <= n; ++i)
    for ( j = 2*i; j <= n; j += i)
        phi[j] -= phi[i];
        for(i=1;i<=n;i++)
           t=t+2*phi[i];
        fprintf(g,"%lld",t+1);

return 0;
}