#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std ;
#define int                 long long
#define ull                 unsigned long long int
#define ld                  long double
#define vi                  vector<int>
#define vii                 vector<pair<int,int>>
#define vvi                 vector<vector<int>>
#define pii                 pair<int,int>
#define pb                  push_back
#define prec(x)             fixed<<setprecision(15)<<x
#define all(x)              x.begin(),x.end()
#define rall(x)             x.rbegin(),x.rend()
#define rev(x)              reverse(x.begin(),x.end())
#define mset(a,b)           memset(a,b,sizeof(a))
#define mcpy(a,b)           memcpy(a,b,sizeof(a))
#define fo0(i,n)            for(int i=0,i##end=n;i<i##end;i++)
#define fo1(i,n)            for(int i=1,i##end=n;i<=i##end;i++)
#define fo(i,a,b)           for(int i=a,i##end=b;i<=i##end;i++)
#define foe(i,x)            for(__typeof((x).end())i=(x).begin();i!=(x).end();++i)
#define fre(i,x)            for(__typeof((x).rend())i=(x).rbegin();i!=(x).rend();++i)
#define mk(arr,n,type)      type *arr=new type[n];
#define dbg(x) cerr << #x << " is " << x << endl;
#define FAST_IO ios_base::sync_with_stdio(false); cin.tie(0);cout.tie(0)
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;
int gcd(int a, int b) { return b ? gcd(b, a%b) : a; }
clock_t beg = clock();
const int inf=1e18;const int mod=1e9+7;const int N=2e5+9;
const double pi = 3.1415926535897932384626433;
void FILE_IO(){
#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
}
#define MAXN   10000001 
  
int spf[MAXN]; 

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; 
        } 
    } 
} 
  
vector<int> getFactorization(int x) 
{ 
    vector<int> ret; 
    while (x != 1) 
    { 
        ret.push_back(spf[x]); 
        x = x / spf[x]; 
    } 
    return ret; 

}
  
void JH(){
    int d=0,e=0,f=0,g=0,p=0,w=0,flag=0,ans=1,res=0,cnt=0,sum=0;double f1=0.0,f2=0.0,f3=0.0;
    sieve();
    int n;cin>>n;
    if(n==1){
        cout<<1;
        return;
    }
    for(int i=2;i<=n;i++){
        vi v=getFactorization(i);
        map<int,int> m;
        for(int j: v){
            m[j]++;
        }
        int prod=1;
        for(auto j: m){
            prod*=(j.second+1);
        }
        ans+=i*prod;
    }
    cout<<ans;

}

int32_t main()
{
    FILE_IO();FAST_IO;int t=1;
    // cin>>t;
    while(t--){JH();}cerr<<fixed<<setprecision(3)<<(double)(clock()-beg)/1000<<"s ";
}

Measured memory_bytes: 81964