mathlib

61f63649 - feat(number_theory/arithmetic_function): Möbius inversion for `add_comm_group`s, `comm_group`s (#5115)

feat(number_theory/arithmetic_function): Möbius inversion for `add_comm_group`s, `comm_group`s (#5115) Adds scalar multiplication for `arithmetic_function`s Generalizes Möbius inversion to work with `(add_)comm_group`s Co-authored-by: jalex-stark <alexmaplegm@gmail.com>