kolakoski.cs

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        foreach (var item in GetSequence().Take(50))
        {
            Console.Write(item.ToString() + ", ");
        }
    }

    private static IEnumerable<int> GetSequence()
    {
        var queue = new Queue<int>();
        int current = 1;
        while (true)
        {
            yield return current;
            queue.Enqueue(current);

            var currentRun = queue.Dequeue();
            if (currentRun == 2)
            {
                yield return current;
                queue.Enqueue(current);
            }

            current = 3 - current;
        }
    }
}

1, 22, 11, 2, 1, 22, 1, 22, 11, 2, 11, 22, 1, 2, 11, 2, 1, 22, 11, 2, 11, 2, 1, 22, 1, 22, 11, 2, 1, 22, 1, 2, 11

Length of the queue grows as O(n/3) (i.e. for 1000th sequence element the queue length is 333)

As the sequence grows, numbers of 1, 2, 11 and 22 all grow approximately equally

http://oeis.org/A000002