# catalan
![C(5) = 42 noncrossing partitions of a 5-element set](https://upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Noncrossing_partitions_5.svg/220px-Noncrossing_partitions_5.svg.png)

A small function for calculating [Catalan numbers](https://en.wikipedia.org/wiki/Catalan_number).

## usage
[![NPM](https://nodei.co/npm/catalan.png?mini)](https://www.npmjs.com/package/catalan)
```js
> const catalan = require('catalan')
> catalan(5)
42

> catalan(-1)
NaN
```

## see also
- [`semibran/narayana`](https://github.com/semibran/narayana) - calculate Narayana numbers

## license
[MIT](https://opensource.org/licenses/MIT) © [Brandon Semilla](https://git.io/semibran)


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catalan

catalan

usage

see also

license

Keywords

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