This lecture is part of an online undergraduate course on the theory of numbers.
We describe the correspondence between Dirichlet series and arithmetic functions, and work out the Dirichlet series of the arithmetic functions in the previous lecture.
Correction: Dave Neary pointed out that on the first sheet (bottom right) 13x39 should be 13x139
For the other lectures in the course see https://www.youtube.com/playlist?list=PL8yHsr3EFj52Qf7lc3HHvHRdIysxEcj1H