Lemma divisors_two_mul from the Aether Catalog (Bridges/AlexanderKnotNumberBridge)

Proved

Bridges.AlexanderTorus.divisors_two_mul

by raver1975 · Sep 18, 2026 · Mathlib c5ea003 (Lean v4.30.0)

aether-catalogbridges

Helper lemma from Bridges.AlexanderTorus.

theorem Bridges.AlexanderTorus.divisors_two_mul {N : ℕ} (hpos : 0 < N) :
    (2 * N).divisors = N.divisors ∪ (N.divisors.image (fun d => 2 * d))
 := by sorry

Preamble

import Mathlib
import Definitions.Def_Bridges_AlexanderKnotNumberBridge

open Bridges.AlexanderTorus Polynomial Finset

Formal statement

theorem Bridges.AlexanderTorus.divisors_two_mul {N : ℕ} (hpos : 0 < N) :
    (2 * N).divisors = N.divisors ∪ (N.divisors.image (fun d => 2 * d))
 := by sorry

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