Extension: Harder Sequences and Patterns

You might recall that we have encountered the famous Fibonacci sequence. There is a world of sequences out there — you can even make your own! To get you started, here is a fun one. Observe the following sequence and try to figure out the pattern: $$1, 11, 21, 1211, 111221, 312211, 13112221\cdots$$ Can you figure out the next number?

HINT: it might help to read the numbers out loud!