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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<int> a(n);
    for(auto &&v : a) cin >> v;
    sort(a.begin(), a.end());
    ll ans = 0;
    for(int i = 0, j = 0, p; i < n; ){
        p = i;
        while(i < n && a[i] == a[p]) i++;
        while(j < n && a[j] < a[p] * 2) j++;
        ll c = i - p;
        ans += c * (c - 1) / 2 * (j - c);
    }
    cout << ans << '\n';
}