- Hogfather is the 20th Discworld novel by Terry Pratchett, and a 1997 British Fantasy Award nominee. It was first released in 1996 and published by Victor Gollancz. It came in 137th place in The Big Read, a BBC survey of the most loved British books of all time, making it one of fifteen books by Pratchett in the Top 200.
- Catalan number (Wikipedia)
In combinatorial mathematics, the Catalan numbers are a sequence of natural numbers that occur in various counting problems, often involving recursively defined objects. They are named after the French-Belgian mathematician Eugène Charles Catalan.