Question Number 90470 by Asif Hypothesis last updated on 23/Apr/20
$${For}\:{any}\:{positive}\:{integer}\:{n},\:\tau\left({n}\right)\:{is}\:{the}\:{number}\:{of}\:{its}\:{factors}\: \\ $$$${Prove}, \\ $$$$\sum_{{i}=\mathrm{1}} ^{{n}} \tau\left({i}\right)=\sum_{{i}=\mathrm{1}} ^{{n}} \lfloor{n}/{i}\rfloor \\ $$