---
tag: 5WG7MPH4ZD
kind: concept
name: Lah number
aliases: [lah-numbers, unsigned-lah-number]
sources:
  - wikipedia: en:85752@r1375382536
    locator: Lah number
    note: adopted
    mention: wikipedia://en/85752
    sections: [Summary]
same_as:
  wikidata: Q451829
  wikipedia: Lah number
inventory: [SCQMJSK188]
---

## Summary

In mathematics, the (**signed and unsigned**) **Lah numbers** are coefficients expressing rising factorials in terms of falling factorials and vice versa. They were discovered by Ivo Lah in 1954. Explicitly, the unsigned Lah numbers $L(n, k)$ are given by the formula involving the [[binomial coefficient|092GEF38YD]]