#include <bits/stdc++.h>
using namespace std;
                     
#define int             long long
#define ld              long double
#define mp              make_pair
#define ff              first
#define ss              second
#define pb              push_back
#define fo(i,n)         for(i=0;i<n;i++)
#define fo1(i,n)        for(i=1;i<=n;i++)
#define FO(i,k,n)       for(i=k;k<=n?i<=n:i>=n;k<=n?i++:i--)
#define all(c)          c.begin(),c.end()
#define rall(c)         c.rbegin(),c.rend()
#define si              set<int>
#define vi              vector<int>
#define mii             map<int,int>
#define pii             pair<int,int>
#define vpii            vector<pii>
#define vvi             vector<vi>
#define usi             unordered_set<int>
#define umii            unordered_map<int,int>
#define pqmx            priority_queue<int>
#define pqmn            priority_queue<int,vi,greater<int> >
#define sp(x)           cout<<setprecision(x)<<fixed;
#define setbits(x)      __builtin_popcountll(x)
#define zerobits(x)     __builtin_ctzll(x)
#define in(a,n)         vi a(n);fo(i,n)cin>>a[i];
#define in1(a,n)        vi a(n+1);fo1(i,n)cin>>a[i];
#define w(t)            int t;cin>>t;while(t--)
#define gcd             __gcd
#define lcm(x,y)        x*(y/gcd(x,y))
#define endl            '\n'
#define PI              3.14159265358979323846
const int inf =         1e18;
const int mod =         1e9+7;
void __p(int x) {cout<<x;}
void __p(int32_t x){cout<<x;}
void __p(float x){cout<<x;}
void __p(double x){cout<<x;}
void __p(ld x) {cout<<x;}
void __p(char x){cout <<'\''<<x<<'\'';}
void __p(const char *x){cout <<'\"' <<x<<'\"';}
void __p(const string &x) {cout<<'\"'<<x<<'\"';}
void __p(bool x) {cout<<(x?"true":"false");}
void _p() {cout << "]\n";}
template<typename T,typename V>     void __p(const pair<T,V> &x) {cout<<'{';__p(x.first);cout<<',';__p(x.second);cout<<'}';}
template<typename T>                void __p(const T &x) {int f = 0; cout << '{'; for (auto &i: x) cout << (f++ ? "," : ""), __p(i); cout << "}";}
template <typename T,typename... V> void _p(T t, V... v) {__p(t);if(sizeof...(v))cout<<", ";_p(v...);}
int po(int x,int p,int m = inf) {int ans=1;x%=m;while(p>0){if(p&1)ans=(ans*x)%m;p=p>>1;x=(x*x)%m;}return ans;}
int inv(int x,int m=mod){return po(x,m-2,m)%m;}
#ifndef ONLINE_JUDGE
#define dbg(x...) cout<<"["<<#x<<"]=[";_p(x)
#else 
#define dbg(x...)
#endif
//=================================================================================




const int N=1e7+5;
int n,m,k,x,y,z,b,c,d,i,j,l,r,f;

bool done[N];
vector < int > primes;
 
void FindPrime(){
    done[1] = 1;
    for(int i=2;i<=N;i++){
        if(done[i]) continue;
        for(int j=i*2;j<=N;j+=i){
            done[j] = 1;
        }
        primes.push_back(i);
    }
}
 
int solve(int Num){
    int Ans=1;
    for(auto p:primes){
        if(p*p*p > Num) break;
        int Count = 1;
        while(Num%p == 0){
            Num /= p,Count++;
        }
        Ans *= Count;
    }
    int sq = sqrt(Num);
    if(!done[Num]) Ans *= 2;
    else if(sq*sq == Num && !done[sq]) Ans *= 3;
    else if(Num != 1) Ans *= 4;
    return Ans;
}



void sol()
{   FindPrime();
    cin>>n;
    c=0;
    fo1(i,n)c+=i*solve(i);
    
    
    
    cout<< c <<endl;
}





int32_t main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    //sp(10);
    // w(t)
    sol();
    return 0;
}

Measured memory_bytes: 21328