#include<bits/stdc++.h>
using namespace std;
//#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
//#define vec vector<ll>
//#define mat vector<vector<ll> >
#define fi first
#define se second
#define double long double
typedef int ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
//typedef long double ld;
typedef complex<double> Complex;
const ll INF=1e9+7;
const ll MOD=998244353;
//const ll inf=INF*INF;
const ll mod=MOD;
const ll MAX=100010;




signed main(){
    ll n;cin>>n;
    ll ans=0;
    vector<ll>d(n+1,1);
    for(int i=sqrt(n)+1;i>=2;i--){
        ll k=i*i;
        ll z=i*i;
        while(k<=n){
            if(d[k]==1)d[k]=i;
            k+=z;
        }
    }
    vector<ll>cnt(n+1);
    REP(i,1,n+1){
        ll di=d[i];
        ll x=i/di/di;
        ans=ans+cnt[x];
        cnt[x]++;
    }
    ans*=2;
    ans+=n;
    cout<<ans<<endl;
}