#include <stdio.h>

int main(int argc, char **argv)
{
    int i, n;

    FILE *f = fopen("fractii.in", "rb");
    fscanf(f, "%d\n", &n);
    fclose(f);

    long long phi[n+1];
    for(i=2; i<=n; i++)
        phi[i] = i;

    for(int i=2; i<=n; i++)
        if(phi[i] == i)
            for(int j=i; j<=n; j+=i)
                phi[j] = phi[j] * (i-1) / i;


    long long total = 0;
    for(int i=2; i<=n; i++)
        total += phi[i];

    f = fopen("fractii.out", "wb");
    fprintf(f, "%lld\n", 2 * total + 1);
    fclose(f);
}