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

const int N = 1e5 + 5;

int a[N] = {0};

void solve() {
	int n;
	cin >> n;
	for (int i = 1; i <= n; ++i) cin >> a[i], a[i] -= i;
	map<int,priority_queue<int>> m;
	for (int i = 1; i <= n; ++i) m[a[i]].push(a[i] + i);
	int ans = 0;
	for (auto x:m) {
		auto& t = x.second;
		while (t.size() >= 2) {
			int aa = t.top();
			t.pop();
			int bb = t.top();
			t.pop();
			if (aa + bb < 0) break;
			ans += aa + bb;
		}
	}
	cout << ans << '\n';
}

signed main() {
	ios::sync_with_stdio(false), cin.tie(nullptr);
	int T; cin >> T;
	while (T--) solve();
}