And the winner is...

Jonathan! Very impressive!

He correctly answered the riddle I posted last week. J, as promised you will receive a note of congratulations in the mail. I'm completely impressed, because I wouldn't have been able to figure it out. I'm not good at those things.

Here's the riddle again, and an explanation.
What is the next series of numbers?
1
11
21
1211
111221
312211
13112221

Answer: 1113213211
Each line is a phrase telling the line previous to it. For example, the second line says that there is "one one" in the line before it. The third line remarks that there are "two ones" in the second line. In the last line, there is "one one, one three, two ones, three twos, one one".