摘要: $$\begin{eqnarray}&\sum_{i=1}^{n}\sum_{j=1}^{n}ij\gcd(i,j)\\&\sum_{d=1}^{n}\sum_{i=1}^{n}\sum_{j=1}^{n}ij[\gcd(i,j)=d] \\&\sum_{d=1}^{n}d^3\sum_{i=1}^ 阅读全文
posted @ 2021-03-13 11:57 HKHbest 阅读(65) 评论(0) 推荐(0) 编辑
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