/// Heil Hitler :P
#include <cstdio>
#include <iostream>
#include <string>
#include <cstring>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <algorithm>
#include <new>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <set>
#define CLR(o) memset(o, 0x00, sizeof o)
#define CLR1(o) memset(o, -1, sizeof o)
#define MAX3(a, b, c) MAX(a , MAX(b,c))
#define MIN3(a, b, c) MIN(a , MIN(b,c))
#define takei(a) scanf("%d", &a)
#define takell(a) scanf("%lld", &a)
#define takellu(a) scanf("%llu", &a)
#define sf scanf
#define ssf sscanf
#define pb push_back
#define PPP system("pause")
#define ok cout << "OK" <<endl;
#define pf printf
#define PI 2*acos(0)
#define READ(a) freopen(a,"r",stdin);
#define WRITE(b) freopen(b, "w", stdout);
using namespace std;

template <class T> T MAX(T a, T b) { return a>b?a:b;}template <class T> T MIN(T a, T b) { return a<b?a:b;}
template <class T1> void deb(T1 p) { cout << "Debugging: " << p << endl;}
template <class T1, class T2> void deb(T1 p, T2 q) { cout << "Debugging: " << p << "\t" << q  << endl;}
template <class T1, class T2, class T3> void deb(T1 p, T2 q, T3 r) { cout << "Debugging: " << p << "\t " << q << "\t " << r << endl;}
template <class T1, class T2, class T3, class T4> void deb(T1 p, T2 q, T3 r, T4 s) { cout << "Debugging: " << p << "\t " << q << "\t " << r << "\t " << s << endl;}
const int xx[] = {0, 0, 1, -1, -1, 1, -1, 1};const int yy[] = {1, -1, 0, 0, 1, 1, -1, -1}; const int kx[] = {-2, -1, 1, 2, 2, 1, -1, -2}; const int ky[] = {1, 2, 2, 1, -1, -2, -2, -1};   // KX-> Knight moovs xx-> diagonal -> 8 horizontal/vertical->4
#define SIZE 4000009
long long *phi;

void PHII()
{
    phi = new long long[SIZE];
    int i, j, k, l;
    for(i=2; i<SIZE; i++)
        phi[i] = i;
    for(i=2; i<SIZE; i++)
        if(phi[i]==i)
    {
        for(j=i; j<SIZE; j+=i)
            phi[j] -= phi[j]/i;
    }
    //for(i=2; i<13; i++)        deb(i, phi[i]);
}

int main()
{
    // time_t t1=clock();
#ifndef ONLINE_JUDGE
    READ("input.txt");
    //WRITE("output.txt");
#endif
    ///                                    MAIN
    PHII();
    long long i, j, k, l, a, b, c, *p;
    p = new long long[SIZE];
    CLR(p);
    for(i=2; i<4000001; i++)
    {
        p[i]+=phi[i]+p[i-1];
        for(j=i*2, k=2; j<4000001; j+=i, k++)
        {
            p[j] += (i*phi[k]);
        }
    }
    while(sf("%lld", &i)==1 &&i)
        pf("%lld\n", p[i]);
        delete(p);
        delete(phi);
    /* Coding is FUN  */
    ///                                    ENDD
    // time_t t2=clock();
    // cout << " My time: " <<(t2-t1) << endl;;
    return 0;
}