#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
//	mt19937 engine((unsigned ll)time(NULL));
//	uniform_int_distribution<ll> distribution(0, (ll)1e18);
//	auto generator = bind(distribution, engine);
//	ll x = generator();
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// #define ordered_set tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update>
// #define ordered_multiset tree<int, null_type, less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>
using namespace std;
void _main();
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	_main();
	return 0;
}
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using vi = std::vector<int>;
using vvi = std::vector<vi>;
using vl = std::vector<ll>;
using vii = std::vector<pair<int, int> >;
using vvl = std::vector<vl>;
using vll = std::vector<pair<ll , ll> >;
using vd = std::vector<double>;
using vvd = std::vector<vd>;
using vs = std::vector<std::string>;
using vvs = std::vector<vs>;
using vb = std::vector<bool>;
using vvb = std::vector<vb>;
using vc = std::vector<char>;
using vvc = std::vector<vc>;
using pii = std::pair<int, int>;
using pll = std::pair<ll, ll>;
using piil = std::pair<pair<int, int>, ll>;
using mii = std::map<int, int>;
using mll = std::map<ll, ll>;
using pql = std::priority_queue<ll>;
using pqi = std::priority_queue<int>;
using pqiil = std::priority_queue<pair<pair<int, int>, ll> >;
using pqii = std::priority_queue<pair<int, int> >;

#define pb push_back
#define ps push
#define eb emplace_back
#define is insert
#define er erase
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define sf(i) sizeof(i)
#define endl "\n"
#define all(v) (v).begin(), (v).end()
#define rep(i, L, R) for(ll i = L;i<=R;i++)
#define pcis precision
#define sz(a) ((ll) a.size())

template<typename T>
struct infinity {
	static constexpr T max=std::numeric_limits<T>::max();
	static constexpr T min=std::numeric_limits<T>::min();
	static constexpr T value=std::numeric_limits<T>::max()/2;
	static constexpr T mvalue=std::numeric_limits<T>::min()/2;
};
template<typename T>constexpr T INF=infinity<T>::value;
constexpr ll lINF=INF<ll>;
constexpr int iINF = INF<int>;
constexpr ld PI = 3.1415926535897932384626;



void _main() {

	ll N;
	cin >> N;
	ll A[N+1];
	rep(i,1,N) cin >> A[i];
	map<ll, ll>	mp;
	rep(i,1,N) mp[A[i]]++;

	vl lst;
	rep(i,1,N) lst.pb(A[i]);
	sort(all(lst));
	lst.erase(unique(all(lst)), lst.end());

	ll S[N+1];
	memset(S,0,sf(S));
	ll M = lst.size();
	ll RES = 0;
	rep(i,0,M-1) S[i] = S[max((ll) 0, i-1)] + mp[lst[i]];
//	rep(i,0,M-1) cout << S[i] << " ";
//	cout << endl;

	for (auto [x, y] : mp) {
		ll left = 0;
		ll right = M-1;
		ll can = 0;
//		cout << "at " << x << " -> " << y << endl;
		while (left <= right) {
			ll mid = (left+right)/2;
			if (lst[mid] < 2*x) {
				left = mid+1;
				can=mid;
			} else {
				right=mid-1;
			}
		}
//		cout << S[can]-y << endl;
		RES += (S[can] - y)*(y*(y-1)/2);
	}
	cout << RES << endl;
}