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

using i64 = long long;
using u64 = unsigned long long;
#define Z cout << "\n"
#define lb lower_bound
#define ub upper_bound
#define inf 0x3f3f3f3f
#define INF 0x3f3f3f3f3f3f3f3f
#define unq(x) sort(x.begin(), x.end()), x.erase(unique(x.begin(), x.end()), x.end())
#define D(x) cerr << #x << ": " << (x) << "\n"
#define DV(v) cerr<< #v << ": "; for(int i=0;i <(v).size(); i++)cerr << ((v)[i]) << ",";cerr << "\n"
#if 0
#define int i64
#endif

void solve() {
    int n;
    cin >> n;

    vector<int>a(n + 1);
    unordered_map<int, vector<int>>mp;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        mp[a[i] - i].push_back(a[i]);
    }

    i64 ans = 0;
    for (auto [x, y] : mp) {
        if (y.size() > 1) {
            sort(y.begin(), y.end(), greater<int>());
            for (int i = 0; i + 1 < y.size(); i += 2) {
                ans += max(0, y[i] + y[i + 1]);
            }
        }
    }
    cout << ans << "\n";
}

signed main() {
    cin.tie(0)->sync_with_stdio(false);
    int t;
    cin >> t;
    while (t--)solve();
    return 0;
}