#ifdef __LOCAL
#define _GLIBCXX_DEBUG
#include "debug2.h"
#endif
#ifndef __LOCAL
#define show(...) 
#define SET_GROUP(x)
#define SET_MAXCNT(x)
#endif

#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
//#include <boost/multiprecision/cpp_int.hpp>
//using bigint = boost::multiprecision::cpp_int;
#define SIZE(x) (int)(x.size())
#define ALL(x) x.begin(),x.end()
using ll = long long;
//int di[] = {1, 0, -1, 0, 1, -1, -1, 1};
//int dj[] = {0, 1, 0, -1, 1, 1, -1, -1};
template<class T>bool chmin(T& x,T y){if(x>y){x=y;return true;}return false;}
template<class T>bool chmax(T& x,T y){if(x<y){x=y;return true;}return false;}
template<class T>vector<T>matrix(int n1,T val){return vector<T>(n1,val);}
template<class T>vector<vector<T>>matrix(int n1,int n2,T val){return vector<vector<T>>(n1,matrix<T>(n2,val));}
template<class T>vector<vector<vector<T>>>matrix(int n1,int n2,int n3,T val){return vector<vector<vector<T>>>(n1,matrix<T>(n2,n3,val));}
template<class T>vector<vector<vector<vector<T>>>>matrix(int n1,int n2,int n3,int n4,T val){return vector<vector<vector<vector<T>>>>(n1,matrix<T>(n2,n3,n4,val));}
template<class T>T sum(vector<T>x){T r=0;for(auto e:x)r+=e;return r;}
template<class T>T max(vector<T>x){T r=x[0];for(auto e:x)chmax(r,e);return r;}
template<class T>T min(vector<T>x){T r=x[0];for(auto e:x)chmin(r,e);return r;}
template<class T>set<T>toSet(vector<T>x){set<T> r;for(auto e:x)r.emplace(e);return r;}
template<class T>map<T,ll>toMap(vector<T>x){map<T,ll>mp;for(auto e:x)mp[e]++;return mp;}
template<class T>vector<T>toVector(set<T>x){vector<T> r;for(auto e:x)r.push_back(e);return r;}
template<class T1,class T2>pair<T1,T2> operator+(pair<T1,T2>x,pair<T1,T2>y){return make_pair(x.first+y.first,x.second+y.second);}
template<class T1,class T2>pair<T1,T2> operator-(pair<T1,T2>x,pair<T1,T2>y){return make_pair(x.first-y.first,x.second-y.second);}
template<class T1,class T2>istream&operator>>(istream&is,tuple<T1,T2>&x){cin>>get<0>(x)>>get<1>(x);return is;}
template<class T1,class T2,class T3>istream&operator>>(istream&is,tuple<T1,T2,T3>&x){cin>>get<0>(x)>>get<1>(x)>>get<2>(x);return is;}
template<class T1,class T2>istream&operator>>(istream&is,pair<T1,T2>&x){cin>>x.first>>x.second;return is;}
template<class T>istream&operator>>(istream&is,vector<T>&x){for(auto&&e:x)is>>e;return is;}
template<class T>istream&operator>>(istream&is,vector<vector<T>>&x){for(auto&&e:x)for(auto&&f:e)is>>f;return is;}
template<class T>ostream&operator<<(ostream&os,const vector<T>&x){for(auto e:x)os<<e<<" ";return os;}
template<class T>ostream&operator<<(ostream&os,const vector<vector<T>>&x){for(auto e:x){for(auto f:e)os<<f<<" ";os<<"\n";}return os;}

int main(){
    int n;
    cin >> n;
    vector<ll> a(n);
    cin >> a;
    sort(ALL(a));
    map<ll, ll> mp = toMap(a);

    ll ans = 0;
    for(const auto& [e, f] : mp){
        ll tmp = f * (f - 1) / 2;

        //1~2*e-1 
        ll cnt = lower_bound(ALL(a), 2 * e) - a.begin() - f;
        chmax(cnt, 0LL);
        tmp *= cnt;
        ans += tmp;
    }
    cout << ans << endl;
    return 0;
}