#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
using lli=long long int;
using ld=long double;
using vi=vector<int>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vvvvi=vector<vvvi>;
using vl=vector<lli>;
using vvl=vector<vl>;
#define rep(i,s,e) for(int i=s;i<e;i++)
#define rrep(i,s,e) for(int i=s-1;i>=e;i--)
#define in(v,tem) for(auto v:tem)
#define veci(v,s) vi v(s); rep(i,0,s) cin >> v.at(i);
#define vecl(v,s) vl v(s); rep(i,0,s) cin >> v.at(i);
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()
using pii=pair<int,int>;
using pll=pair<lli,lli>;
#define mp(f,s) make_pair(f,s)
#define fi first
#define se second
using vpii=vector<pii>;
using vpll=vector<pll>;
#define vecpii(v,s) vpii v(s); rep(i,0,s) cin >> v.at(i).fi >> v.at(i).se;
#define vecpll(v,s) vpll v(s); rep(i,0,s) cin >> v.at(i).fi >> v.at(i).se;
#define pub(x) push_back(x)
#define puf(x) push_front(x)
#define pob(x) pop_back(x)
#define pof(x) pop_front(x)
#define eb(x) emplace_back(x)
#define print(s) cout << s << endl;
const int I_INF=1<<30;
const lli LL_INF=1ll<<60;
const string alp="abcdefghijklmnopqrstuvwxyz";
const int let=alp.size(); // 26

template<typename T> inline vector<T> cood_comp(vector<T> &seq){
  vector<T> ret=seq;
  sort(seq.begin(),seq.end());
  seq.erase(unique(seq.begin(),seq.end()),seq.end());
  for(int i=0;i<(int)ret.size();i++){
    ret.at(i)=lower_bound(seq.begin(),seq.end(),ret.at(i))-seq.begin();
  }
  return ret;
}

int main(){
  int n; cin >> n;
  veci(a,n);
  vi c=cood_comp(a);

  vl imos(a.size(),0);
  rep(i,0,n) imos[c[i]]++;
  rep(i,1,a.size()) imos[i]+=imos[i-1];

  lli ans=0;
  rep(i,0,a.size()){
    lli eq=(i==0 ? imos[i]:imos[i]-imos[i-1]);
    if(eq<2) continue;
    int ind=lower_bound(all(a),a[i]*2)-a.begin()-1;
    if(ind<0) continue;
    lli neq=imos[ind]-eq;
    ans+=eq*(eq-1)/2*neq;
  }

  print(ans);
}