#include <bits/stdc++.h>
using namespace std;

//#define int long long
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define rep(i,n) for(int i=0;i<n;++i)
#define rep1(i,n) for(int i=1;i<n;++i)
#define exrep(i, a, b) for(ll i = a; i < b; i++)
#define out(x) cout << x << endl
#define EPS (1e-7)
#define gearup ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef vector<string> vs;
typedef vector<pair<int,int> > vpii;
typedef vector<vector<int> > vvi;
typedef vector<vector<char> > vvc;
typedef vector<vector<bool> > vvb;
typedef vector<vector<double> > vvd;
typedef vector<vector<string> > vvs;
typedef vector<ll> vl;
typedef vector<vector<ll> > vvl;
typedef vector<vector<vector<ll> > > vvvl;
ll MOD = 1000000007;
const long long L_0 = 1LL << 60;
const int INF = 2147483647; // 2^31-1
const double PI = acos(-1);
//cout<<fixed<<setprecision(10);

template<class T> inline bool chmin(T& a, T b) {if (a > b) {a = b;return true;}return false;}
template<class T> inline bool chmax(T& a, T b) {if (a < b) {a = b;return true;}return false;}
template<class T> void debug(T v){rep(i,v.size()) cout<<v[i]<<" ";cout<<endl;}
const ll dx[8] = {1, 1, 0, -1, -1, -1, 0, 1};
const ll dy[8] = {0, 1, 1, 1, 0, -1, -1, -1};
//以降 cin の入力元が 'input.txt' になる
//std::ifstream in("input.txt");
//std::cin.rdbuf(in.rdbuf());

struct mint {
    long long x;
    mint(long long x=0):x((x%MOD+MOD)%MOD){}
    mint operator-() const { return mint(-x);}
    mint& operator+=(const mint a) {
        if ((x += a.x) >= MOD) x -= MOD;
        return *this;
    }
    mint& operator-=(const mint a) {
        if ((x += MOD-a.x) >= MOD) x -= MOD;
    	return *this;
    }
    mint& operator*=(const mint a) {
    	(x *= a.x) %= MOD;
    	return *this;
    }
    mint operator+(const mint a) const {
        mint res(*this);
        return res+=a;
    }
    mint operator-(const mint a) const {
        mint res(*this);
        return res-=a;
    }
    mint operator*(const mint a) const {
        mint res(*this);
        return res*=a;
    }
    mint pow(long long t) const {
        if (!t) return 1;
        mint a = pow(t>>1);
        a *= a;
    	if (t&1) a *= *this;
        return a;
    }
    // for prime MOD
    mint inv() const {
        return pow(MOD-2);
    }
    mint& operator/=(const mint a) {
    	return (*this) *= a.inv();
    }
    mint operator/(const mint a) const {
        mint res(*this);
        return res/=a;
    }
};
 
 /*  PrimeFact
    init(N): 初期化。O(N log log N)
    get(n): クエリ。素因数分解を求める。O(log n)
 */
template <typename T>
struct PrimeFact {
    vector<T> spf;
    PrimeFact(T N) { init(N); }
    void init(T N) { // 前処理。spf を求める
        spf.assign(N + 1, 0);
        for (T i = 0; i <= N; i++) spf[i] = i;
        for (T i = 2; i * i <= N; i++) {
            if (spf[i] == i) {
                for (T j = i * i; j <= N; j += i) {
                    if (spf[j] == j) {
                        spf[j] = i;
                    }
                }
            }
        }
    }
    map<T, T> get(T n) { // nの素因数分解を求める
        map<T, T> m;
        while (n != 1) {
            m[spf[n]]++;
            n /= spf[n];
        }
        return m;
    }
};

ll me[10000001]; //メモ化
///nの約数を追加する(nを含む)
ll divisor_pick(ll n){
    if(n % 3 == 0)return (me[n] = me[n/3]*2);
    if(n % 2 == 0)return (me[n] = me[n/2]*2);
    if(n % 5 == 0)return (me[n] = me[n/5]*2);
    vl a;
    for(ll i=1LL;i*i<=n;i++){
        if(n%i == 0){
            a.push_back(i);
            if(n/i != i)a.push_back(n/i);
        }
    }
    return (me[n] = a.size());
}

signed main()
{   
    gearup;
    ll n; cin >> n;
    ll res = 0;
    PrimeFact<ll> pf(n+10);
    for(ll i=1;i<=n;i++){
        auto num = pf.get(i);
        ll now = 1;
        for(auto p:num)now *= p.second + 1;
        res += i * now;
    }
    out(res);
}



Measured memory_bytes: 81304