Yesterday I noticed for the first time the "Music" feature of Neil J.A. Sloane's Online Encyclopedia of Integer Sequences, which connects the OEIS's number sequences with Jonathan Middleton's Musical Algorithms site.
So, of course, I immediately listened to sequence A000108, the Catalan numbers, which (among many other things) count the number of ways to arrange n matching pairs of parentheses, or the number of full binary trees with n+1 leaves, or the number of Dyck words of length 2n:
1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, …
This is not the first time that I've posted Dyck music on Language Log — see the discussion and the examples in "Starlings" (4/26/2006). Unlike that earlier example, however, this one has no particular point, other than that OEIS is fun.
If you agree, please contribute to the OEIS foundation. Or just watch the movie: