n = int(input())
a = [int(x) for x in input().split()]

assert 3 <= n <= 3 * 10 ** 5
for x in a:
    assert 1 <= x <= 10 ** 9

from collections import defaultdict

cnt = defaultdict(int)
for x in a:
    cnt[x] += 1

a = list(sorted(set(a)))

ans = 0
s = 0
for c in cnt.values():
    s += c * (c - 1) // 2
    ans -= c * c * (c - 1) // 2

idx = 0
for x in a:
    while a[idx] * 2 <= x:
        c = cnt[a[idx]]
        s -= c * (c - 1) // 2
        idx += 1
    ans += s * cnt[x]
print(ans)