#include <iostream>
#include <iomanip>//小数点出力用
//cout << fixed << setprecision(10) << ans;
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
using ll = long long;
using namespace std;
#define modPHash (ll)((1LL<<61)-1)
#define modP (ll)998244353
bool chkrng0idx(int pos, int sup) { return (0 <= pos && pos < sup); }
int clk4(int num) { return (num - 2) * (num % 2); }
void yn(bool tf) { cout << (tf ? "Yes\n" : "No\n"); }

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N;
    cin >> N;
    vector<int>A(N);
    for (int i = 0;i < N;i++)cin >> A[i];
    sort(A.begin(), A.end());
    int now = -1;
    ll combo = 0;
    ll ans = 0;
    for (int i = 0;i <= N;i++) {
        if (i != N && A[i] == now) {
            combo++;
        }
        else {
            ll u = lower_bound(A.begin(), A.end(), now * 2) - A.begin() - combo;
            ans += (u * (combo - 1) * combo) >> 1;
            combo = 1;
            if (i != N)now = A[i];
        }
    }
    cout << ans;
    return 0;
}