$\sum^n_{i=1}\lfloor\frac{n}{i}\rfloor=\sum^n_{i=1}\sigma(i)\approx nlogn$
by AThousandSuns @ 2018-06-16 23:42:08
调和级数了解一下
by hellomath @ 2018-06-16 23:53:37
调和级数了解一下
by 小粉兔 @ 2018-06-16 23:57:16
下式为调和级数的公式，其中 $r$ 为[欧拉常数](https://baike.baidu.com/item/%E6%AC%A7%E6%8B%89%E5%B8%B8%E6%95%B0)，约为 $0.58$：
$$\lim_{n \to \infty}\Big(\sum_{i=1}^n\frac 1 i\Big)=\ln n+r$$
by hellomath @ 2018-06-17 00:35:25
调和级数了解一下
by Niko @ 2018-06-17 08:20:20
调和级数了解一下
by 夜刀神十香ღ @ 2018-06-17 08:40:58
调和级数了解一下~
by 绝顶我为峰 @ 2018-06-17 09:16:53
~~游泳健身了解一下~~
by 2016gdgzoi471 @ 2018-07-06 11:13:38
@[larryzhong](/space/show?uid=20438) Orz [larryzhong](/space/show?uid=20438)
by Siyuan @ 2018-12-09 19:02:46