English
For any a, the predicate n ↦ Coprime(a, n) is periodic with period a; i.e., Coprime(a, n+a) ↔ Coprime(a, n).
Русский
Для любого a предикат n ↦ Coprime(a, n) периодичен с периодом a; то есть Coprime(a, n+a) ↔ Coprime(a, n).
LaTeX
$$$ \forall n, \operatorname{Coprime}(a, n+a) \iff \operatorname{Coprime}(a, n) $$$
Lean4
theorem periodic_coprime (a : ℕ) : Periodic (Coprime a) a := by
simp only [coprime_add_self_right, forall_const, Periodic]