Data Structures, Algorithms, & Applications in C++
Chapter 18, Exercise 43

We can actually prove a slightly stronger result.



n! = n(n-1)*(n-2)* ... * ceil(n/2) * ... * 1

>= n(n-1)*(n-2)* ... * ceil(n/2)

>= [ceil(n/2)]^ceil(n/2)