#include <bits/stdc++.h>
using namespace std;
using ll=long long;
template <class T> using P=pair<T,T>;

void solve()
{
    int n;
    cin>>n;
    vector<P<ll>> a;
    for(int i=0;i<n;i++)
    {
        int x;
        cin>>x;
        a.push_back({x-i,x});
    }
    ll ans=0;
    sort(a.begin(),a.end(),[](P<ll> a,P<ll> b){if(a.first!=b.first)return a.first<b.first;else return a.second>b.second;});
    for(int i=0;i<n;i+=2)
    {
        if(i+1<n&&a[i].first!=a[i+1].first)
        {
            i--;
            continue;
        }
        if(i+1<n&&a[i].second+a[i+1].second<=0)
        continue;
        if(i+1<n)
        ans+=a[i].second+a[i+1].second;
    }
    cout<<ans<<'\n';
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int t=1;
    cin>>t;
    while(t--)
    solve();
    return 0;
}