Ydoc770

摘要： 0-30-0,数学还只打了暴力，菜就多练 Problem 1. facsum 省流: $$f(n) =(\sum\limits_{d\mid n}\varphi(d))^m(\sum\limits_{d\mid n}\sigma_0(d)\mu(\frac{n}{d})\frac{n}{d})$$ 阅读全文