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

using ll = long long;

int main() {
  int N;
  cin >> N;
  map<ll, ll> mp;
  while(N--) {
    ll a;
    cin >> a;
    mp[a]++;
  }
  const int K = mp.size();
  vector<ll> A = {0}, B = {0}, C = {0};
  for(auto [v, c] : mp) {
    A.push_back(v);
    C.push_back(C.back() + c);
    B.push_back(c);
    // cout << "# " << B.back() << " " <<  c << endl;
  }
  ll ans = 0;
  for(int i = 1; i <= K; i++) {
    int p = lower_bound(A.begin(), A.end(), 2 * A[i]) - A.begin() - 1;
    // cout << A[i] << " " << B[i] << " " << C[i] << " : " << p << " " << C[p] << endl;
    ans += B[i] * (B[i] - 1) / 2 * (C[p] - B[i]);
    // cout << ans << endl;
  }
  cout << ans << endl;
}