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

using i64 = long long;

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);

    auto solve = [&]() {
        int n;
        cin >> n;

        vector<int> a(n);
        for (int i = 0; i < n; i++) {
            cin >> a[i];
        }

        sort(a.begin(), a.end());

        i64 ans = 0;

        for (int i = 0, j = 0; i < n; i = j) {
            while (j < n && a[i] == a[j]) {
                j++;
            }
            ans += 1LL * (j - i) * (j - i - 1) / 2 * (lower_bound(a.begin(), a.end(), 2 * a[i]) - a.begin() - (j - i));
        }

        cout << ans << '\n';
    };
    
    solve();
    
    return 0;
}