#include <bits/stdc++.h>
using namespace std;

int main(){
    int N;
    cin >> N;
    vector<int> A(N);
    for (int i = 0; i < N; i++){
        cin >> A[i];
    }
    
    map<int, long long> counter;
    for (int a : A) {
        counter[a]++;
    }
    
    vector<int> values;
    vector<long long> counts;
    for (auto &p : counter) {
        values.push_back(p.first);
        counts.push_back(p.second);
    }
    
    vector<long long> acc_counts(counts.size() + 1, 0);
    for (int i = 0; i < counts.size(); i++){
        acc_counts[i + 1] = acc_counts[i] + counts[i];
    }
    
    long long ans = 0;
    for (int i = 0; i < values.size(); i++){
        int v = values[i];

        auto it = lower_bound(values.begin(), values.end(), 2 * v);
        int idx = it - values.begin();
        
        ans += acc_counts[idx] * counts[i] * (counts[i] - 1) / 2;
        ans -= counts[i] * counts[i] * (counts[i] - 1) / 2;
    }
    
    cout << ans << endl;
    return 0;
}