#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long; 
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)


int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n; cin >> n;
    set<int> s;
    map<int, ll> mp;
    vi a(n);
    rep(i, n){
        cin >> a[i];
        s.insert(a[i]);
        mp[a[i]]++;
    }
    sort(all(a));
    ll ans = 0;
    ll low = 0;
    for(auto i : s){
        ll base = mp[i]*(mp[i]-1)/2;
        ll cnt = lower_bound(all(a), 2*i) - upper_bound(all(a), i);
        ans += base*cnt + base*low;
        low += mp[i];
    }
    cout << ans << endl;


    return 0;
}