#include<bits/stdc++.h>
#define int long long
#define pb push_back
#define P pair<int,int>
#define f first 
#define s second
using namespace std;
void solve(){
    int n;
    cin>>n;
    int a[n];
    vector<P>b;
    for(int i=0;i<n;i++){
        cin>>a[i];
        b.push_back({i-a[i],i});
    }
    sort(b.begin(),b.end(),greater<P>());
    map<int,int>mp;
    int ans=0;
    for(int i=0;i+1<n;i++){
        if(b[i].f==b[i+1].f&&mp[b[i].s]==0&&mp[b[i+1].s]==0&&b[i].s-b[i].f+b[i+1].s-b[i+1].f>=0){
            ans+=b[i].s-b[i].f+b[i+1].s-b[i+1].f;
            mp[b[i].s]=1;
            mp[b[i+1].s]=1;
        }
    }
    cout<<ans<<endl;
    return;
}


signed main(){
    int _=1;
    cin>>_;
    while(_--){
        solve();
    }
}