theorem
proved
term proof
sigma_mul_of_coprime
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formal statement (Lean)
769theorem sigma_mul_of_coprime {k m n : ℕ} (h : Nat.Coprime m n) :
770 sigma k (m * n) = sigma k m * sigma k n := by
proof body
Term-mode proof.
771 simp only [sigma]
772 exact ArithmeticFunction.isMultiplicative_sigma.map_mul_of_coprime h
773
774/-- σ_0(mn) = σ_0(m) × σ_0(n) for coprime m, n. -/