#include"bits/stdc++.h"
using namespace std;
#define ALL(x) begin(x),end(x)
#define rep(i,n) for(int i=0;i<(n);i++)
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define mod 998244353
using ll=long long;
const int INF=1000000000;
const ll LINF=1001002003004005006ll;
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return true;}return false;}

struct IOSetup{
    IOSetup(){
        cin.tie(0);
        ios::sync_with_stdio(0);
        cout<<fixed<<setprecision(12);
    }
} iosetup;
 
template<typename T>
ostream &operator<<(ostream &os,const vector<T>&v){
    for(int i=0;i<(int)v.size();i++) os<<v[i]<<(i+1==(int)v.size()?"":" ");
    return os;
}
template<typename T>
istream &operator>>(istream &is,vector<T>&v){
    for(T &x:v)is>>x;
    return is;
}

vector<bool> sieve(int n){
    vector<bool> ret(n+1,true);
    ret[0]=false;
    if(n>0) ret[1]=false;
    for(int i=2;i*i<=n;i++){
        if(!ret[i]) continue;
        for(int j=i*2;j<=n;j+=i) ret[j]=false;
    }
    return ret;
}

vector<bool> isP=sieve(50000010);

signed main(){
    int N;cin>>N;
    vector<int> V(N+1);
    rep(i,N+1) V[i]=i;

    for(int i=2;i<=N;i++)if(isP[i]){
        for(int j=i;j<=N;j+=i){
            int c=0;
            while(V[j]%i==0) c++,V[j]/=i;
            if(c&1) V[j]*=i;
        }
    }

    vector<ll> cnt(N+1,0);
    ll ans=0;
    for(int i=1;i<=N;i++){
        ans+=cnt[V[i]]*2+1;
        cnt[V[i]]+=1;
    }
    cout<<ans<<endl;
    return 0;
}