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
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>> sum(n!,n,1,10) in> sum(n!,n,1,10)
计算 !5
