#include <bits/stdc++.h>
using namespace std;
const int MXN = (int)4e5 + 7;
const int MOD = (int)998244353;
int n, a[MXN], mod[MXN], k;
void add_mn(int a, int b) {
  int sum = a + b;
  int l = sum - (b - 1);
  mod[l]++;
  mod[sum]--;
  if (l > 2) {
    mod[2] += 2;
    mod[l] -= 2;
  }
}
void add_mx(int a, int b) {
  int sum = a + b;
  int r = (k - a) + sum;
  mod[sum + 1]++;
  mod[r + 1]--;
  mod[r + 1] += 2;
}
void solve() {
  cin >> n >> k;
  fill(mod + 2, mod + (2 * k) + 1, 0);
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  for (int i = 1; i <= n / 2; i++) {
    if (a[i] > a[n - i + 1]) swap(a[i], a[n - i + 1]);
  }
  for (int i = 1; i <= n / 2; i++) {
    add_mx(a[i], a[n - i + 1]);
    add_mn(a[i], a[n - i + 1]);
  }
  int sum = 0, mn = MOD;
  for (int i = 2; i <= 2 * k; i++) {
    sum += mod[i];
    mn = min(mn, sum);
  }
  cout << mn << endl;
}
signed main() {
  int t;
  ios_base::sync_with_stdio(0);
  cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}
