#include <bits/stdc++.h>
// python->C++翻訳
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N;
    if (!(cin >> N)) return 0;
    vector<long long> A(N);
    for (int i = 0; i < N; ++i) cin >> A[i];

    // n = isqrt(4 * 10**5)
    const long long n = (long long)floor(sqrt(400000.0L));

    long long ans = 0;

    // d : defaultdict(int)
    unordered_map<long long, long long> d;
    d.reserve((size_t)N * 2);
    d.max_load_factor(0.7f);

    // for ni in range(1, n+1):
    for (long long ni = 1; ni <= n; ++ni) {
        // for j in range(N):
        for (int j = 0; j < N; ++j) {
            long long key = A[j] - (long long)(j + 1) * ni;
            long long need = -key; // -(A[j] - (j+1)*ni)
            auto it = d.find(need);
            if (it != d.end()) ans += it->second;
            d[key] += 1;
        }
        d.clear();
    }

    // for ij in range(1, n+1):
    for (long long ij = 1; ij <= n; ++ij) {
        for (int j = 0; j < N; ++j) {
            long long i = ij - j - 2; // i = ij-j-2
            if (0 <= i && i < j && j < N) {
                long long s = A[(int)i] + A[j];
                if (s % ij == 0) {
                    long long ni = s / ij;
                    if (ni > n) ans += 1;
                }
            }
        }
    }

    cout << ans << '\n';
    return 0;
}