Zeta Function (English)

There is more below.
Ниже есть продолжение.







When you look closer, you can figure out that this prove is actually "reverse prove" from part 2. In part 2 you use fundamental theorem of arithmetic to get rid of the problem of removing infinitely many numbers, that's why , I guess, it is used as "standard prove". Nevertheless, this "proof" helps to develop intuition why this equation holds.








To be continued.