#include <iostream>
#include <algorithm>
#include <utility>
#include <map>
#include <vector>
using namespace std;
using ll = long long;
using pil = pair<int, ll>;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N; cin>>N;
    map<int, ll> M;
    for (int i=0;i<N;i++){
        int A; cin>>A;
        M[A]++;
    }
    int K = M.size();
    vector<pil> edge;
    vector<ll> S(K+1, 0);
    for (auto p: M){
        edge.push_back(p);
    }
    sort(edge.begin(), edge.end());
    for (int i=1;i<=K;i++) S[i]=S[i-1]+edge[i-1].second;

    ll ans = 0;
    int right = 0;
    for (int left=0;left<K;left++){
        while(right<K && edge[right].first<2*edge[left].first) right++;
        ans += edge[left].second*(edge[left].second-1)/2LL*(S[right]-edge[left].second);
    }
    cout << ans << "\n";
    return 0;
}