腦力勞動

2023-05-26 20:01 作者:虞廷采風人 0人讀過 | 我要投稿

$S(x)%3D%5Csum_%7Bk%3D0%7D%5E%7B%E2%88%9E%7D%20%7B%20k%2Bm%2B1%20%5Cchoose%20m%2B1%20%7D%5Cfrac%7Bx%5Ek%20%7D%7Bk!%7D%20$

解：

$S(x)%3D%5Csum_%7Bk%3D0%7D%5E%7B%E2%88%9E%7D%20%7B%20k%2Bm%2B1%20%5Cchoose%20k%20%7D%5Cfrac%7Bx%5Ek%20%7D%7Bk!%7D%20%3D%5Csum_%7Bk%3D0%7D%5E%7B%E2%88%9E%7D%20%7B%20k%2Bm%20%5Cchoose%20k-1%20%7D%5Cfrac%7Bx%5Ek%20%7D%7Bk!%7D%20%2B%5Csum_%7Bk%3D0%7D%5E%7B%E2%88%9E%7D%20%7B%20k%2Bm%20%5Cchoose%20k%20%7D%5Cfrac%7Bx%5Ek%20%7D%7Bk!%7D%20$

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