from collections import defaultdict

n = int(input())
a = list(map(int, input().split()))

assert 2 <= n <= 2 * 10 ** 5
for x in a:
    assert 1 <= x <= 2 * 10 ** 5


lim = 400010

ans = 0
for k in range(1, lim):
    cnt = defaultdict(int)
    for i in range(1, n + 1):
        if i * k >= lim: break
        p = k*i-a[i-1]
        ans += cnt[-p]
        cnt[p] += 1

print(ans)