#include <bits/stdc++.h>
#define ll long long
#define rep(i,s,t) for(int i=(s);i<=(t);i++)
#define rev_rep(i,s,t) for(int i=(s);i>=(t);i--)
using namespace std;
ll ci(){ ll x; scanf("%lld", &x); return x; }

enum{N=500023};

int main(){
	int T = ci();
	while( T-- ){
		map<int, vector<int> > mp;
		ll n = ci();
		rep(i,1,n){
			ll x = ci();
			mp[x-i].push_back(x);
		}
		ll ans = 0;
		for(auto [i,vec]:mp){
			sort(vec.begin(), vec.end(), greater<int>() );
			int n = vec.size();
			rep(i,0,n-1) if( i%2==1 ) {
				ans += max(0, vec[i]+vec[i-1]);
			}
		}
		printf("%lld\n", ans);
	}
	return 0;
}