# Factorial/Related Articles

From Citizendium, the Citizens' Compendium

*See also changes related to Factorial, or pages that link to Factorial or to this page or whose text contains "Factorial".*

## Parent topics

- Combinatorics [r]: Branch of mathematics concerning itself, at the elementary level, with counting things.
^{[e]} - Special function [r]: Various families of solution functions corresponding to cases of the hypergeometric equation or functions used in the equation's study, such as the gamma function.
^{[e]} - Meromorphic functions [r]: Function of complex variables which is analytic in its domain of definition save at a finite number of points which are poles.
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## Subtopics

- Stirling's formula [r]: An approximation to the factorial function far from the negative part of the real axis.
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- Binomial coefficient [r]: The number of possible choices of
*k*elements out of*n*elements, disregarding order.^{[e]} - Gamma function [r]: A mathematical function that extends the domain of factorials to non-integers.
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