#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1e9 + 7;
const long long INF = 1e18;
const double PI = acos(-1.0);
const int MAXN = (int)3e5 + 7;
void solve() {
  int n, k;
  cin >> n >> k;
  int a[n], pref[2 * k + 1], temp[2 * k + 1];
  memset(temp, 0, sizeof pref);
  for (int i = 0; i < (int)n; ++i) cin >> a[i];
  int occ[2 * k + 1];
  memset(occ, 0, sizeof occ);
  for (int i = 0; i < (int)n / 2; ++i) {
    int s = a[i] + a[n - i - 1];
    ++occ[s];
    ++temp[min(a[i], a[n - i - 1]) + 1];
    --temp[max(a[i], a[n - i - 1]) + k + 1];
  }
  for (int i = 2; i <= 2 * k; ++i)
    pref[i] = temp[i] + (i == 2 ? 0 : pref[i - 1]);
  int ans = INT_MAX;
  for (int i = 2; i <= 2 * k; ++i)
    ans = min(ans, pref[i] - occ[i] + n - 2 * pref[i]);
  cout << ans << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  int t;
  cin >> t;
  while (t--) solve();
  return 0;
}
