from math import isqrt
from collections import defaultdict
N=int(input())
A=list(map(int,input().split()))
n=isqrt(4*(10**5))
ans=0
d = defaultdict(int)
for ni in range(1,n+1):
    for j in range(N):
        ans+=d[-(A[j]-(j+1)*ni)]
        d[(A[j]-(j+1)*ni)]+=1
    d.clear()

for ij in range(1,n+1):
    for j in range(N):
        i = ij-j-2
        if 0<=i<j<N:
            ni = (A[i]+A[j])//ij
            if (A[i]+A[j])%ij==0 and ni>n:
                ans+=1
print(ans)