#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
 #define int long long

#define all(X) (X).begin(), (X).end()
#define reset(X) memset(X, 0, sizeof(X))
#define mp(a, b) make_pair(a, b)
#define pb push_back
#define endl '\n'
#define fi first
#define se second


using namespace __gnu_pbds;
using namespace std;
const int mod=1e9+7;
 // const int mod=998244353;
 // const int mod=1e9+9;
const int INF=4e18+10;
// const int INF=4e18+10;
template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template <typename T>
using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define read(n) int n; cin>>n;
#define readv(x, n) vector<int> x(n); for(auto &i:x) cin>>i;


typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef pair<int, int> pii;

template<typename T1,typename T2>
void set_min(T1& a, T2 b)
{
    a=min(a, (T1)b);
}


int multiply(int a, int b, int in_mod){return (a*b)%in_mod;}
int mult_identity(int a){return 1;}


auto power(auto a, int b, int in_mod)
{
    auto prod=mult_identity(a);
    auto mult=a%in_mod;
    while(b!=0)
    {
        if(b%2)
        {
            prod=multiply(prod,mult, in_mod);

        }
        mult=multiply(mult, mult,in_mod);
        b/=2;
    }
    return prod;
}
int mod_inv(int q, int in_mod)
{

    return power(q, in_mod-2,in_mod);
}
const int MAXN = 1e7+10;
vector<int> ans(MAXN + 100, 1);

void precomp()
{
    int N = MAXN;
    vector<int> lp(N+1);
    vector<int> pr;

    for (int i=2; i<=N; ++i) {
        if (lp[i] == 0) {
            lp[i] = i;
            pr.push_back (i);
        }
        for (int j=0; j<(int)pr.size() && pr[j]<=lp[i] && i*pr[j]<=N; ++j)
            lp[i * pr[j]] = pr[j];
    }


    ans[1] = 1;
    for(int i=2;i<=N;i++)
    {
        ans[i] = i;
        int temp = i;
        int last = -1;
        int when = 0;
        while(temp > 1)
        {
            int l = lp[temp];
            if(l == last)
            {
                when++;
            }
            else
            {
                last = l;
                ans[i] *= (when+1);
                when = 1;
            }
            temp/=l;
        }
        ans[i] *= (when+1);
        ans[i] += ans[i-1];
    }

}

void solve()
{
    int n ;
    cin>>n;
    cout<<ans[n]<<endl;

}


signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
#ifndef ONLINE_JUDGE
    if (fopen("INPUT.txt", "r"))
    {
        freopen("INPUT.txt", "r", stdin);
        freopen("OUTPUT.txt", "w", stdout);
    }
#endif
    auto clk = clock();
    mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
    // -------------------------------------Code starts here---------------------------------------------------------------------
    precomp();
    int t = 1;
    // cin>>t;

    for (int test = 1; test <= t; test++)
    {
        // cout<<"Case #"<<test<<": ";
        // cout<<endl;
        solve();
        // cout<<endl;
    }

    // -------------------------------------Code ends here------------------------------------------------------------------

    clk = clock() - clk;
    // cerr << fixed << setprecision(6) << "Time: " << ((long double)clk) / CLOCKS_PER_SEC << "\n";
    return 0;
}


Measured memory_bytes: 167868