// g++-14 1.cpp -std=c++20 -O2 -I .
#include <bits/stdc++.h>
using namespace std;

#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

// #include<ext/pb_ds/assoc_container.hpp>
// #include<ext/pb_ds/tree_policy.hpp>
// #include<ext/pb_ds/tag_and_trait.hpp>
// using namespace __gnu_pbds;

#include <atcoder/math>
#include <atcoder/modint>
using namespace atcoder;

using ll = long long;
using ld = long double;
 
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vld = vector<ld>;
using vvld = vector<vld>;
using vst = vector<string>;
using vvst = vector<vst>;

#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define pq_big(T) priority_queue<T,vector<T>,less<T>>
#define pq_small(T) priority_queue<T,vector<T>,greater<T>>
#define all(a) a.begin(),a.end()
#define rep(i,start,end) for(ll i=start;i<(ll)(end);i++)
#define per(i,start,end) for(ll i=start;i>=(ll)(end);i--)
#define uniq(a) sort(all(a));a.erase(unique(all(a)),a.end())

random_device seed;
mt19937_64 randint(seed());

ll grr(ll mi, ll ma) { // [mi, ma)
    return mi + randint() % (ma - mi);
}

int sq = 40;

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

  int n;cin>>n;
  vi a(n+1,0);
  rep(i,1,n+1){
    // cin>>a[i];
    a[i]=grr(1,2e5+1);
  }

  ll ans=0;

  auto start=clock();

  rep(x,1,sq+1){
    // Ai + Aj = x (i + j)
    unordered_map<int,int> mp;
    rep(i,1,n+1){
      ll tar=a[i]-x*i;
      ans+=mp[-tar];
      mp[tar]++;
    }
  }

  auto mid=clock();
  cerr<<(ld)(mid-start)/(CLOCKS_PER_SEC)<<endl;

  int lim=min(8010,n);
  rep(i,1,lim+1){
    rep(j,i+1,lim+1){
      if((a[i]+a[j])%(i+j)==0){
        ll x=(a[i]+a[j])/(i+j);
        if(x>sq)ans++;
      }
    }
  }

  cout<<ans<<endl;

  auto fin=clock();
  cerr<<(ld)(fin-start)/(CLOCKS_PER_SEC)<<endl;
}