#include<bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int, int> PII;
void solve()
{
    int n;
    std:: cin >> n;
    set <int> s;
    for(int i = 2; i <= n; i ++ )
    {
        s.insert(i);
    }

    vector<PII> l;
    while(1)
    {
        int x;
        for(auto p : s)
        {
            x = p;
            break;
        }
        int y = 2 * x;
        if(s.find(y) != s.end())
        {
            l.push_back({x, y});
            s.erase(y);
            s.erase(x);
        }
        else
        {
            break;
        }
    }

    std:: cout << l.size();
    for(auto p : l)
    {
        std:: cout << " " << p.first << " " << p.second;
    }
    std:: cout << endl;
}   
signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
    int T;
    std:: cin >> T;
    while(T -- )
	solve();
	return 0;
}