#include <iostream>
#include <string>
#include <vector>
using namespace std;

int count(const string& s) {
    int n = s.length();
    if (n == 1) {
        return 0;
    }
    vector<int> count(26, 0);
    for (char c : s) {
        count[c - 'a']++;
    }
    int pairs = 0;
    for (int c : count) {
        pairs += c * (c - 1) / 2;
    }
    return pairs;
}

int main() {
    int t;
    cin >> t; 
    while (t--) {
        int n;
        cin >> n; 
        string s;
        cin >> s; 
        int pairs = count(s);
        cout << pairs << endl;
    }
    return 0;
}