This problem is not for judgement. It is okay not to be able solve it. Because even great mathematician John Conway couldn’t figure it out at first.
But give it a try then I will share the answer.

Find the pattern and continue the sequence:
1, 11, 21, 1211, 111221, 312211, 13112221…

Hint: To solve it you only need to now how to count 🙂

Obstacles are things a person sees when he takes his eyes off his goal.
—E. Joseph Cossman