#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
using ll = long long;
using pll = pair<ll, ll>;

set<ll> s, thr;
map<ll, ll> m;
vector<ll> v, cnt;

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0); cout.tie(0);

  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    v.push_back(x);
    s.insert(x);
    m[x]++;
  }
  vector<ll> p(s.begin(), s.end());
  cnt = vector<ll>(s.size()+1);

  ll sum = 0;
  for (int i = 0; i < v.size(); i++) {
    int vidx = lower_bound(p.begin(), p.end(), v[i]) - p.begin();
    int idx = upper_bound(p.begin(), p.end(), v[i]/2) - p.begin();
    if (idx <= vidx) cnt[idx]++, cnt[vidx]--, cnt[vidx+1]++;
    else cnt[idx]++;
  }

  for (int i = 0; i < cnt.size()-1; i++) {
    // cout << cnt[i] << " ";
    if (i) cnt[i] += cnt[i-1];
    ll w = p[i];
    sum += m[w]*(m[w]-1)/2*cnt[i];
  }
  cout << sum;
}