---
tag: 0TKP3TDD02
kind: concept
name: Bell numbers
msc: [11B73]
sources:
  - url: https://en.wikipedia.org/wiki/Bell_number
    locator: Set partitions
same_as:
  wikidata: Q816063
  wikipedia: Bell number
---

## Summary

The Bell numbers $B_n$ count all the partitions of an $n$-element set. They are the row sums of the Stirling numbers of the second kind. The node [[Bell numbers|0WW85SQVS3]] gives the precise definition.