// Created by Kshitij Anand NSIT
#include <bits/stdc++.h>
//#include <ext/numeric>
//using namespace __gnu_cxx;


using namespace std;


#define int long long
#define pb push_back
#define P pair<int,int>
#define F first
#define S second
#define vi vector<int>
#define vc vector<char>
#define vb vector<bool>
#define all(x) x.begin(),x.end()
#define sz(x) (int)x.size()
#define mp(a, b) make_pair(a, b)
#define min3(a, b, c) min(min(a, b), c)
#define min4(a, b, c, d) min(min(a, b), min(c, d))
#define max3(a, b, c) max(max(a, b), c)
#define max4(a, b, c, d) max(max(a, b), max(c, d))
#define fill(arr,val) memset(arr,val,sizeof(arr))
#define inf 1e18
#define ps(x,y) fixed<<setprecision(y)<<x
#define db(x)  cout<<#x<<" : "<<x<<endl
// #define M 10000000


const int N = 1000000007;


const int MAX = 10000001; 
  
// array to store prime factors 
int factor[MAX] = { 0 }; 
  
// function to generate all prime factors 
// of numbers from 1 to 10^6 
void generatePrimeFactors() 
{ 
    factor[1] = 1; 
  
    // Initializes all the positions with their value. 
    for (int i = 2; i < MAX; i++) 
        factor[i] = i; 
  
    // Initializes all multiples of 2 with 2 
    for (int i = 4; i < MAX; i += 2) 
        factor[i] = 2; 
  
    // A modified version of Sieve of Eratosthenes to 
    // store the smallest prime factor that divides 
    // every number. 
    for (int i = 3; i * i < MAX; i++) { 
        // check if it has no prime factor. 
        if (factor[i] == i) { 
            // Initializes of j starting from i*i 
            for (int j = i * i; j < MAX; j += i) { 
                // if it has no prime factor before, then 
                // stores the smallest prime divisor 
                if (factor[j] == j) 
                    factor[j] = i; 
            } 
        } 
    } 
} 
  
// function to calculate number of factors 
int calculateNoOFactors(int n) 
{ 
    if (n == 1) 
        return 1; 
  
    int ans = 1; 
  
    // stores the smallest prime number 
    // that divides n 
    int dup = factor[n]; 
  
    // stores the count of number of times 
    // a prime number divides n. 
    int c = 1; 
  
    // reduces to the next number after prime 
    // factorization of n 
    int j = n / factor[n]; 
  
    // false when prime factorization is done 
    while (j != 1) { 
        // if the same prime number is dividing n, 
        // then we increase the count 
        if (factor[j] == dup) 
            c += 1; 
  
        /* if its a new prime factor that is factorizing n,  
           then we again set c=1 and change dup to the new  
           prime factor, and apply the formula explained  
           above. */
        else { 
            dup = factor[j]; 
            ans = ans * (c + 1); 
            c = 1; 
        } 
  
        // prime factorizes a number 
        j = j / factor[j]; 
    } 
  
    // for the last prime factor 
    ans = ans * (c + 1); 
  
    return ans; 
} 

void solve(){

    int n,a,b,c, ans=0, count=0, sum=1;
    cin>>n;

    // seive();
    generatePrimeFactors(); 
    
    for(int i=1; i<=n; i++) {

      ans += i*calculateNoOFactors(i);
    }

    cout<<ans<<endl;
    // cout<<primes[n-1]<<endl;


}

int32_t main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
    
    
  //  int t; cin>>t; while(t--)
    {     
      solve();
    }

  return 0;
}


Measured memory_bytes: 81748