#include <bits/stdc++.h>
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("-O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ;
  int t;
  cin >> t;
  while (t--) {
    int n, k;
    unordered_map<int, int> cnt;
    cin >> n >> k;
    vector<int> a(n);
    vector<int> pref(2 * k + 2, 0);
    for (int i = (0); i < (n); i++) {
      cin >> a[i];
    }
    for (int i = (0); i < (n / 2); i++) {
      int v1 = a[i];
      int v2 = a[n - 1 - i];
      cnt[v1 + v2]++;
      pref[min(v1, v2) + 1] += 1;
      pref[max(v1, v2) + k + 1] -= 1;
    }
    for (int i = (1); i < (pref.size()); i++) {
      pref[i] += pref[i - 1];
    }
    int ans = (int)1e9;
    for (int i = 2; i <= 2 * k; i++) {
      int cur = pref[i] - cnt[i];
      cur += (n / 2 - pref[i]) * 2;
      ans = min(ans, cur);
    }
    cout << ans << "\n";
  }
  return 0;
}
