#include<bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using mint=modint998244353; //1000000007;
using ll=long long;
using pp=pair<int,int>;
#define sr string 
#define vc vector
#define fi first
#define se second
#define rep(i,n) for(int i=0;i<(int)n;i++)
#define pb push_back
#define all(v) v.begin(),v.end()
#define pque priority_queue
#define bpc(a) __builtin_popcount(a)
int main(){
  int n;cin>>n;
  vc<bool>v(n+1,true); 
  vc<int>sqs;
  for(int i=2;i*i<=n;i++){
    sqs.pb(i*i);
    for(int j=i*i;j<=n;j+=i*i)v[j]=false;
  }
  int r=sqs.size();
  ll ans=0;
  for(int i=1;i<=n;i++)if(v[i]){
    while(r&&sqs[r-1]*i>n)r--;
    ans+=(ll)(r+1)*(r+1);
  }
  cout<<ans;
}