#include<bits/stdc++.h>

using namespace std;
int main(){
    int t; cin>>t;
    while(t--){
        int n,k; cin>>n>>k;
        int arr[200005];
        for(int i=0; i<n; ++i){
            cin>>arr[i];
        }
        int preSum[400005];
        for(int i=0; i<200005; ++i){
            preSum[i] = 0;
        }
        for(int i=0;i<(n/2); ++i){
            int mn = min(arr[i], arr[n-i-1]);
            int mx = max(arr[i], arr[n-i-1]);
            
            int valMin = mn+1;
            int valMax = min(k*2, mx+k);

            preSum[valMin]+= 1;
            preSum[valMax]+= -1;
        }
        for(int i=1; i<400001; ++i){
            preSum[i] = preSum[i] + preSum[i-1];
        }
        for(int i=0; i<(n/2); ++i){
            preSum[arr[i]+arr[n-1-i]]+=1;
        }
        int mx = -1;
        for(int i=1; i<=2*k; ++i){
            mx = max(mx, preSum[i]);
        }
        cout<<(n-mx)<<"\n";
    }
    return 0;
}