stirling formula(팩토리얼)
https://en.wikipedia.org/wiki/Stirling%27s_approximation
[Stirling’s approximation - Wikipedia
From Wikipedia, the free encyclopedia Approximation for factorials Comparison of Stirling’s approximation with the factorial In mathematics, Stirling’s approximation (or Stirling’s formula) is an approximation for factorials. It is a good approximation, le
en.wikipedia.org](https://en.wikipedia.org/wiki/Stirling%27s_approximation)
팩토리얼은 stirling formula에 근사함
수가 커질수록 오차율이 0에 수렴함