#include <algorithm>
#include <array>
#include <cassert>
#include <cmath>
#include <complex>
#include <cstdint>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

#ifdef _DEBUG
#define DUMP(x) std::cerr << (#x) << " = " << (x) << "\n"
#else
#define DUMP(x)
#endif
#define REP(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define EREP(i, a, b) for (int i = (int)(a); i <= (int)(b); ++i)
#define RREP(i, a, b) for (int i = (int)(a)-1; i >= (int)(b); --i)
#define rep(i, n) REP(i, 0, n)
#define erep(i, n) EREP(i, 0, n)
#define rrep(i, n) RREP(i, n, 0)
#define ALL(r) (r).begin(), (r).end()
#define pb push_back
#define eb emplace_back
#define fi first
#define se second

template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    os << "{";
    rep(i, v.size()) os << v[i] << (i == (int)v.size() - 1 ? "" : ", ");
    os << "}";
    return os;
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    return (os << "(" << p.first << ", " << p.second << ")");
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const map<T, U> &m) {
    bool first = true;
    os << "{";
    for (const auto &e : m) {
        if (!first)
            os << ", ";
        os << "{" << e.first << ": " << e.second << "}";
        first = false;
    }
    os << "}";
    return os;
}
template <typename T>
ostream &operator<<(ostream &os, const set<T> &s) {
    os << "{";
    bool first = true;
    for (const auto &e : s) {
        if (!first)
            os << ", ";
        os << e;
        first = false;
    }
    os << "}";
    return os;
}
template <typename T>
ostream &operator<<(ostream &os, const multiset<T> &s) {
    os << "{";
    bool first = true;
    for (const auto &e : s) {
        if (!first)
            os << ", ";
        os << e;
        first = false;
    }
    os << "}";
    return os;
}
template <typename T>
T dup(T x, T y) {
    return (x + y - 1) / y;
};
template <typename A, size_t N, typename T>
inline void arrayFill(A (&array)[N], const T &val) {
    std::fill((T *)array, (T *)(array + N), val);
}
template <class T>
inline bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template <class T>
inline bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
struct in {
    const size_t n = 0;
    in() = default;
    in(size_t n) : n(n){};
    template <typename T>
    operator T() {
        T ret;
        cin >> ret;
        return ret;
    }
    template <typename T>
    operator vector<T>() {
        assert(n != 0);
        vector<T> ret(n);
        for (T &x : ret) {
            T tmp = in();
            x = tmp;
        }
        return ret;
    }
    template <typename T, typename U>
    operator pair<T, U>() {
        pair<T, U> ret;
        ret.first = in();
        ret.second = in();
        return ret;
    }
};

namespace fiore::impl {
template <typename T>
inline void out_impl(const T &x, char end_char) {
    std::cout << x << end_char;
}
template <typename T>
inline void out_impl(const vector<T> &x, char end_char) {
    bool first = true;
    for (const auto &e : x) {
        if (!first)
            std::cout << ' ';
        std::cout << e;
        first = false;
    }
    std::cout << end_char;
}
} // namespace fiore::impl
template <typename T>
inline void out(const T &x) {
    fiore::impl::out_impl(x, '\n');
};
template <typename T, typename U, typename... Args>
inline void out(const T &x, const U &y, const Args &... args) {
    fiore::impl::out_impl(x, ' ');
    out(y, args...);
}

using ll = int64_t;
using vint = vector<int32_t>;
using vvint = vector<vint>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vstr = vector<string>;
using pint = pair<int32_t, int32_t>;
using vpint = vector<pint>;
using pll = pair<ll, ll>;
using vpll = vector<pll>;
using setint = set<int32_t>;
using qint = queue<int32_t>;
using qpint = queue<pint>;

constexpr std::int32_t INF = 1001001001;
constexpr std::int64_t LINF = 1001001001001001001;

template <typename T>
vector<pair<T, ll>> rle(vector<T> v) {
    vector<pair<T, ll>> ret;
    ret.reserve(v.size() / 2);
    for (const auto x : v) {
        if (ret.empty() || ret.back().first != x) {
            ret.emplace_back(x, 1);
        } else {
            ++ret.back().second;
        }
    }
    return ret;
}
vector<pair<char, ll>> rle(string s) {
    vector<pair<char, ll>> ret;
    ret.reserve(s.size() / 2);
    for (const auto c : s) {
        if (ret.empty() || ret.back().first != c) {
            ret.emplace_back(c, 1);
        } else {
            ++ret.back().second;
        }
    }
    return ret;
}

struct primeSieve {
    ll n;
    vll prime_factor;
    vll primes;

    primeSieve(ll n = 1) : n(n), prime_factor(n + 1, 0) {
        prime_factor[0] = prime_factor[1] = -1;
        for (ll i = 2; i <= n; ++i) {
            if (prime_factor[i])
                continue;
            primes.pb(i);
            prime_factor[i] = i;
            for (ll j = i * i; j <= n; j += i) {
                if (!prime_factor[j])
                    prime_factor[j] = i;
            }
        }
    }
    bool isPrime(ll x) { return prime_factor[x] == x; }
    vll factorList(ll x) {
        vll res;
        while (x != 1) {
            res.pb(prime_factor[x]);
            x /= prime_factor[x];
        }
        return res;
    }
    vpll factor(ll x) { return rle(factorList(x)); }
};

void Main() {
    ll n = in();
    primeSieve ps(n);
    ll ans = 0;
    for (int i = 1; i <= n; ++i) {
        auto v = ps.factor(i);
        ll tmp = 1;
        for (const auto &e : v) {
            tmp *= e.se + 1;
        }
        ans += tmp * i;
    }
    out(ans);
}

signed main() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << std::fixed << std::setprecision(15);
    Main();
    return 0;
}

Measured memory_bytes: 89740