/*
*****************************
* 作者:huzhaoxin            	*
* 努力加油,努力赚钱娶媳妇回家 	*
* 时时刻刻爱老婆            	*
*****************************
*/
#include<bits/stdc++.h>
#define all(x) x.begin(),x.end() 
#define endl "\n"
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
const double eps = 1e-9;
const long long mod = 1e9 + 7;
const long long inf = 2e12 + 7;
/*---------------------------------------------------------------------------*/
void solve() {
	ll n;
	cin>>n;
	vector<ll>x(n+1);
	for(int i=1;i<=n;i++)cin>>x[i],x[i]-=i;
	map<ll,vector<ll>>mp;
	for(int i=1;i<=n;i++){
		mp[x[i]].push_back(x[i]+i);
	}
	ll res=0;
	for(auto it:mp){
		vector<ll>tmp=it.second;
		if(tmp.size()>1)
		for(int i=tmp.size()-1;i>=1;i-=2){
			if(tmp[i]+tmp[i-1]>0){
				res+=tmp[i];
				res+=tmp[i-1];
			}
		}
	}
	cout<<res<<endl;
}
/*---------------------------------------------------------------------------*/
int main() {
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	ll T;
	for (cin >> T; T; T--)
	solve();
	return 0;
}