$$f(i)=\sum_{k\mid i}k^d(i\le n)$$
by pufanyi @ 2018-04-12 16:06:32
@[chen_zhe](/space/show?uid=8457)
by ezoixx130 @ 2018-04-12 16:16:24
@[_pfy_](/space/show?uid=84088) fixed
by chen_zhe @ 2018-04-12 17:12:08