N = int(input())

A = list(map(int,input().split()))

dic = {}

for a in A:
    if a not in dic:
        dic[a] = 0
    dic[a] += 1

ac = [ (na,dic[na]) for na in dic ]
ac.sort()

lgidx = 0
lg = 0

ans = 0

for na,cnt in ac:

    while lgidx < len(ac) and ac[lgidx][0] < na*2:
        lg += ac[lgidx][1]
        lgidx += 1

    other = lg - cnt
    ans += (cnt * (cnt-1) // 2) * other

print (ans)