#include<bits/stdc++.h>
using namespace std;
using ll =long long;


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

    ll N;
    cin>>N;
    ll MX=2e5*2;
    ll an=0;
    vector<map<ll,ll>> M(MX+1);
    for(ll i=1;i<=N;i++){
        ll A;
        cin>>A;
        for(ll k=1;k*i<=MX;k++){
            ll d=A-i*k;
            // cout<<k<<" "<<d<<endl;
            if(M[k].count(-d)){
                an+=M[k][-d];
            }
            M[k][d]++;
        }
    }    
    cout<<an<<"\n";
}