#include <cmath>
#include <deque>
#include <algorithm>
#include <iterator>
#include <list>
#include <tuple>
#include <map>
#include <unordered_map>
#include <queue>
#include <set>
#include <unordered_set>
#include <stack>
#include <string>
#include <vector>
#include <fstream>
#include <iostream>
#include <functional>
#include <numeric>
#include <iomanip> 
#include <stdio.h>
#include <assert.h>
//eolibraries
#define lnf 3999999999999999999
#define inf 999999999
#define fi first
#define se second
#define pb push_back
#define ll long long
#define ld long double
#define all(c) (c).begin(),(c).end()
#define sz(c) (int)(c).size()
#define make_unique(a) sort(all(a)),a.erase(unique(all(a)),a.end())
#define pii pair <int,int>
#define ftpii pair<pii,pii>
#define rep(i,n) for(int i = 0 ; i < n ; i++) 
#define drep(i,n) for(int i = n-1 ; i >= 0 ; i--)
#define crep(i,x,n) for(int i = x ; i < n ; i++)
#define vi vector <int> 
#define vec(...) vector<__VA_ARGS__>
#define fcin ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
//eodefine
using namespace std;

const int _maxn = 5e7+3;

int d[_maxn+100],prm[_maxn+10];

int main(){
fcin;
	rep(i,_maxn) d[i]=i;

	crep(p,2,sqrt(_maxn)+1){
	    if(sqrt(p)==int(sqrt(p)) and d[p]==p){
		    for(int j=p;j<=_maxn;j+=p){
				while(d[j]>1 and d[j]%p==0) d[j]/=p;
			}
		}
	}
	
	rep(i,_maxn) prm[i]=0;
    
    int n;
    cin>>n;
    
    rep(i,n+1){
        prm[d[i]]++;
    }
    
    ll ans=0;
    crep(i,1,n+1){
        ans+=(ll)prm[i]*prm[i];
    }
    
    cout<<ans<<"\n";
/*
*/
	return 0;
}