# Catalan number

> English word · Noun

## Definitions
1. In combinatorial mathematics, any of a sequence of natural numbers that occur in various counting problems, often involving recursively defined objects; the nᵗʰ Catalan number is equal to (2n choose n) over (n+1).

## Etymology
Named after the Belgian mathematician Eugène Catalan (1814–1894).

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/catalan-number