Today I present to you the so-called Catalan numbers, used in combinatorics, and which are a sequence of natural numbers that appear in several counting problems, usually recursive. You'll see how crazy they leave you! Sponsored by Universitat Politècnica de València UPV (http://www.upv.es/) Subscribe to the channel! Follow Eduardo Sáenz de Cabezón: http://twitter.com/edusadeci Follow us on Facebook: www.facebook.com/DerivandoYouTube