Prof. Mary Ann Harasymowycz (Williamsville N.) gave us project on Catalan numbers. They are the numbers that come up when you count things in lots of seemingly different problems, from handshakes, from geometry, from parenthesis forming, etc. They also come up in Pascal’s triangle in several hidden ways.

We hope to have a project sheet up soon. Meanwhile, here is a list of the first few numbers: 1, 1, 2, 5, 14, 42, 132, …