Ken Jennings, the 74-time Jeopardy! champion, has a blog.
Today he wrote about polyominoes, inspired by the question of how many pieces there would be in Tetris if it were played with pieces made of five or six squares instead of the canonical four. He's not a mathematician, and he finds it surprising that there's no nice formula for the number of polyominoes with n cells. I suppose it is kind of surprising to someone with no mathematical training; by this point in my life I've gotten used to the fact that things just don't work that way.