Answer

问题及解答

关于 $!n$

Posted by haifeng on 2020-11-15 10:22:50 last update 2021-05-11 09:39:09 | Edit | Answers (0)

$!n$ 定义为 

\[
!n=1!+2!+3!+\cdots+n!=\sum_{k=1}^{n}k!
\]

 

在 Calculator 中做实验:

 

>> !10
in> !10

out> 4037913

------------------------


>> sum(n!,n,1,10)
in> sum(n!,n,1,10)

out> 4037913

 


计算 !5