/*
    Ujjawal Pabreja [cuber_coder]
*/
#include <bits/stdc++.h> 
#include <functional> 
using namespace std;
using ll = long long;
using ld = long double;
#define speed_cubing    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define rep(i,a)        for(ll i = 0 ; i < a ; i++)
#define repe(i,a,b)     for(ll i = a ; i < b ; i++)
#define bac(i,a)        for(ll i = a ; i >= 0 ; i--)
#define bace(i,a,b)     for(ll i = a ; i >= b ; i--)
#define pb              push_back
#define mp              make_pair
#define in              insert
#define ff              first
#define ss              second
#define vv              vector
#define vll             vector <ll>
#define pll             pair <ll,ll>
#define vpll            vector <pll>
#define umap            unordered_map
#define uset            unordered_set
#define mset            multiset
#define pqueue          priority_queue
#define setbit(x)       __builtin_popcountll(x)
#define init(c,a)       memset(c,a,sizeof(c))
#define all(c)          c.begin(),c.end()
#define sz(c)           (ll)c.size()
#define lb              lower_bound
#define ub              upper_bound
#define maxe            *max_element
#define mine            *min_element
#define rev             reverse
#define Y               "YES"
#define N               "NO"
#define nl              "\n"
#define debug(x)        cout << #x << " : " << x << nl;
const ll inf = 1e18;  
const ll mod = 1e9 + 7;
const ll MOD = 998244353;
const ll MAX = 2e5 + 1;
 
// ====== BigInt begins ======
// #include <boost/multiprecision/cpp_int.hpp>
// using namespace boost::multiprecision;
// ====== BigInt ends ======
 
// ====== PBDS begins ======
// #include <ext/pb_ds/assoc_container.hpp> 
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// typedef tree<pair<int,int>, null_type, less<pair<int,int>>, rb_tree_tag, 
//         tree_order_statistics_node_update> 
//         pbds; 
// ====== PBDS ends ======
 
// ====== Useful functions begin ======
inline ll add(ll a,ll b) {return ((a%mod)+(b%mod))%mod;}
inline ll sub(ll a,ll b) {return ((a%mod)-(b%mod)+mod)%mod;}
inline ll mul(ll a,ll b) {return ((a%mod)*(b%mod))%mod;}
ll pwr(ll x,ll n){
    if(n == 0){
        return 1;
    }
    if(n&1){
        return mul(x, pwr(mul(x, x), (n - 1) / 2));
    } else {
        return pwr(mul(x, x), n / 2);
    }
}
ll modinv(ll n){ 
    return pwr(n, mod - 2); 
}
ll gcd(ll a,ll b) {
    if(b == 0) {
        return a;
    }
    return gcd(b, a % b);
}
// ====== Useful functions end ======
ll p[10000001], dp[10000001];
// ====== Variables begin ======
void speed_solve(){
    ll n;
    cin >> n;
    cout << dp[n];
}
 
int main(){
    speed_cubing;
    ll test_cases = 1;
    // cin >> test_cases;
    rep(i,10000001) p[i] = 1;
    for(ll i = 2 ; i < 10000001 ; i++){
        if(p[i] == 1){
            p[i] = 2;
            ll power = 0, x;
            for(ll j = i * 2 ; j < 10000001 ; j += i){
                x = j;
                power = 0;
                while((x % i) == 0){
                    x /= i;
                    power++;
                }
                p[j] *= (power + 1);
            }
        }
    }
    ll tot = 0;
    rep(i,10000001){
        // cout << p[i] << " ";
        tot += (i * p[i]);
        dp[i] = tot;
    }
    rep(i,test_cases){
        // cout << "Case #" << i + 1 << ": ";
        speed_solve();
    }
    return 0;
}

Measured memory_bytes: 159892