All combinations of a list of objects. All objects down to a lone one, C#

Language: Layout:

//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var source = new List<int>() { 1, 2, 3 };
            var target = new List<List<int>>();

for(var i = 0; i < source.Count; i++)
            {
                for(var j = i; j < source.Count; j++)
                {
                    target.Add(new List<int>(source.Skip(i).Take(source.Count - j)));
                }
            }
            
            // sort the target so it wil be easy to see all permutations
            target = target.OrderBy(t => t[0]).ThenBy(t => t.Count).ToList();
            
            // display inner lists
            target.ForEach(x => Console.WriteLine(string.Join(", ", x)));
            
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,17 sec, absolute running time: 0,11 sec, cpu time: 0,11 sec, average memory usage: 16 Mb, average nr of threads: 3