//#pragma GCC optimize ("Ofast")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("avx,avx2,fma")


#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
#define pb push_back
#define F first
#define S second
#define ins insert
#define mp make_pair
#define bit __builtin_popcount
#define md (l + ((r - l) / 2))
#define all(x) x.begin(),x.end()
//#define all(x , n) x+1,x+n+1
#define eb emplace_back
#define ub upper_bound
#define lb lower_bound
#define sz(x) (int)x.size()
#define ios ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define file(s) if (fopen(s".in", "r")) freopen(s".in", "r", stdin), freopen(s".out", "w", stdout)

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;


using ll = long long;
using ld = long double;

//#define int ll

const int N = 1e7+54, mod = 1e9 + 7, mod1 = 998244353;
const int MAX = 1e5 + 11 , T = 2000;
const int INF1 = 2e9 + 11;
const ll INF2 = 2e18 + 11;
const long double INF3 = 1e8 + 11;
const int base = 500;
const int P = 37;
const int dx[] = {1, -1, 0, 0, 1, 1, -1, -1};
const int dy[] = {0, 0, 1, -1, 1, -1, 1, -1};
const int LOG = 20;
const double EPS = 1e-4;
const double PI = acos(-1.0);

template<typename T> using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T1, typename T2> inline void chmin(T1 &a, T2 b) { if (a > b) a = b; }
template<typename T1, typename T2> inline void chmax(T1 &a, T2 b) { if (a < b) a = b; }


typedef pair <int, int> pii;        // #include <ext/pb_ds/assoc_container.hpp>y01
typedef pair <ll, ll> pll;         // #include <ext/pb_ds/tree_policy.hpp>
typedef vector <int> vi;          // #include <ext/rope>
                                  // #include <ext/rope>
                                 // #include <ext/rope>
bool prime(int n) {             // template<typename T> using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;
    for(int i=2;i<=sqrt(n);i++){
        if(n%i==0){return 0;}
    }return 1;}
int query = 0;
ll bp(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
///////////////////////////////////////////////////////////

int lp[N];

void solve() {
    int n;
    cin >> n;
    for(int i = 2; i < N; i ++) {
        if(lp[i] == 0) {
            lp[i] = i;
            if(i*1ll*i < N)
                for(int j = i*i; j < N; j += i) {
                    if(!lp[j])
                        lp[j] = i;
                }
        }
    }
    ll sum = 0;
    for(int i = 1; i <= n; i ++) {
        ll cur = i;
        int last = 0;
        ll ans = 1;
        ll cnt = 0;
        while(cur != 1) {
            if(last != lp[cur]) {
                ans *= (cnt+1);
                cnt = 1;
                last = lp[cur];
            }
            else {
                cnt ++;
            }
            cur /= lp[cur];
        }
        ans *= cnt+1;
        sum = (sum + (ans*i));
 //       cout << '\n';
    }
    cout << sum;
}

/*
12 13 14


0 1 2 3 4 5 6 7
0 1 2 3 4 5 6 7
0 1 2 3 4 5 6 7
0 1 2 3 4 5 6 7
5 6 7 8 9 10 11 12
+8
+8
+8 -9
+8 -9
+8 -9
+8 -9
+8 -9
+8 -9
+8 -9


*/

main() {
  //  file("A");
   ios;
    int tt = 1;
    if(query == 1)
        cin >> tt;
    if(query == 2)
        tt = INF1;
    while(tt --) {
        solve();
    }
    return 0;
}


Measured memory_bytes: 42728