mathjs/docs/reference/functions/bellNumbers.md

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser and offers an integrated solution to work with numbers, big numbers, complex numbers, units, and matrices.

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# Function bellNumbers

The Bell Numbers count the number of partitions of a set. A partition is a pairwise disjoint subset of S whose union is S.
bellNumbers only takes integer arguments.
The following condition must be enforced: n >= 0


## Syntax

```js
math.bellNumbers(n)
```

### Parameters

Parameter | Type | Description
--------- | ---- | -----------
`n` | Number &#124; BigNumber | Total number of objects in the set

### Returns

Type | Description
---- | -----------
Number &#124; BigNumber | B(n)


## Examples

```js
math.bellNumbers(3); // returns 5;
math.bellNumbers(8); // returns 4140;
```


## See also

[stirlingS2](stirlingS2.md)