#pragma GCC optimize("O3")
                #pragma comment(linker, "/stack:200000000")
                #pragma GCC optimize("unroll-loops")
                 
                #include <algorithm>
                #include <bitset>
                #include <cassert>
                #include <chrono>
                #include <cmath>
                #include <complex>
                #include <cstdio>
                #include <cstdlib>
                #include <cstring>
                #include <ctime>
                #include <deque>
                #include <functional>
                #include <iomanip>
                #include <iostream>
                #include <iterator>
                #include <limits>
                #include <climits>
                #include <list>
                #include <map>
                #include <numeric>
                #include <queue>
                #include <random>
                #include <ratio>
                #include <set>
                #include <sstream>
                #include <stack>
                #include <string>
                #include <unordered_map>
                #include <unordered_set>
                #include <utility>
                #include <vector>
                using namespace std;
                 
                typedef long long ll;
                typedef long double LD;
                #define int ll
                #define double LD
                #define pb push_back
                #define mp make_pair
                #define REP(i,n) for (int i = 0; i < n; i++)
                #define loop(i,n) for (int i = 0; i < n; i++)
                #define FOR(i,a,b) for (int i = a; i < b; i++)
                #define REPD(i,n) for (int i = n-1; i >= 0; i--)
                #define FORD(i,a,b) for (int i = a; i >= b; i--)
                #define remax(a,b) a = max(a,b)
                #define remin(a,b) a = min(a,b)
                #define mem(a, b) memset(a, b, sizeof a)
                #define append push_back
                #define all(v) v.begin(),v.end()
                #define F first
                #define S second
                #define print(x) cout << (x) << endl
                #define PRECISION(x) cout << fixed << setprecision(x)
                #define FAST_IO ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
                #define N 1010
                #define pb push_back
                const double PI=acos(-1);
                const int MOD = 1000000007;
                const int FMOD = 998244353;
                const double eps = 1e-9;
                 
                mt19937 RNG(chrono::steady_clock::now().time_since_epoch().count()); 
                
                
                
                // allowed. 

#define MAXN   10000001 
  
// stores smallest prime factor for every number 
int spf[MAXN]; 
  
// Calculating SPF (Smallest Prime Factor) for every 
// number till MAXN. 
// Time Complexity : O(nloglogn) 
void sieve() 
{ 
    spf[1] = 1; 
    for (int i=2; i<MAXN; i++) 
  
        // marking smallest prime factor for every 
        // number to be itself. 
        spf[i] = i; 
  
    // separately marking spf for every even 
    // number as 2 
    for (int i=4; i<MAXN; i+=2) 
        spf[i] = 2; 
  
    for (int i=3; i*i<MAXN; i++) 
    { 
        // checking if i is prime 
        if (spf[i] == i) 
        { 
            // marking SPF for all numbers divisible by i 
            for (int j=i*i; j<MAXN; j+=i) 
  
                // marking spf[j] if it is not  
                // previously marked 
                if (spf[j]==j) 
                    spf[j] = i; 
        } 
    } 
} 
  
int divc(int x){
	int tot = x,prev = -1,pc=0,ls;
	vector<int> bck;
	while(x > 1){
		if(prev == -1 || prev != spf[x]){
			tot *= (pc+1);
			pc = 1;
			prev = spf[x];
		}
		else{
			pc++;
		}
		ls = spf[x];
		x /= spf[x];
	}
	tot *= (pc+1);
	return tot;
}

signed main()
{
    sieve(); 
    
    int n;
    cin>>n;
    
    int ans=0;
    for(int x=1;x<=n;x++){
     ans += divc(x); 
    }
    cout<<ans;
}

Measured memory_bytes: 81688