func_code_string: #include <bits/stdc++.h>   #define ll long long int   #define vi vector<ll>   #define vvi vector<vector<ll>>   #define pii pair<ll, ll>   #define pb push_back   #define rep0(i, n) for(ll i = 0;i<n;i++)   #define rep1(i, n) for(ll i = 1;i<n;i++)   #define all(v) v.begin(),v.end()   #define fast                                 ios_base::sync_with_stdio(false);        cin.tie(NULL);                           cout.tie(NULL);   using namespace std;   const int N = 1e5 + 5;      void solve(){       ll n;       cin >> n;       vector<ll> arr(n);       for(ll i=0; i<n; i++){           cin >> arr[i];           arr[i] = arr[i]-i-1;       }       map<ll, ll> mp;       ll res = 0;       for(ll i=0; i<n; i++){           if(mp[arr[i]]>0){               res += mp[arr[i]];           }           mp[arr[i]]++;       }       cout << res <<   n ;   }      int main()   {       fast;       int t;       cin >> t;       while(t--){           solve();       }       return 0;   }   