theorem
proved
omega_threehundredsixty
show as:
view math explainer →
open explainer
Generate a durable explainer page for this declaration.
open lean source
IndisputableMonolith.NumberTheory.Primes.ArithmeticFunctions on GitHub at line 657.
browse module
All declarations in this module, on Recognition.
explainer page
formal source
654theorem omega_fortyfive : omega 45 = 2 := by native_decide
655
656/-- ω(360) = 3 (prime factors are 2, 3, 5). -/
657theorem omega_threehundredsixty : omega 360 = 3 := by native_decide
658
659/-- ω(840) = 4 (prime factors are 2, 3, 5, 7). -/
660theorem omega_eighthundredforty : omega 840 = 4 := by native_decide
661
662/-! ### Radical (product of distinct prime factors) -/
663
664/-- The radical of n is the product of its distinct prime factors. -/
665def radical (n : ℕ) : ℕ := n.primeFactors.prod id
666
667/-- rad(1) = 1. -/
668theorem radical_one' : radical 1 = 1 := by native_decide
669
670/-- rad(2) = 2. -/
671theorem radical_two' : radical 2 = 2 := by native_decide
672
673/-- rad(6) = 6 (squarefree). -/
674theorem radical_six' : radical 6 = 6 := by native_decide
675
676/-- rad(12) = 6. -/
677theorem radical_twelve' : radical 12 = 6 := by native_decide
678
679/-- rad(p) = p for prime p. -/
680theorem radical_prime' {p : ℕ} (hp : Prime p) : radical p = p := by
681 have hp' : Nat.Prime p := (prime_iff p).1 hp
682 simp only [radical]
683 rw [Nat.Prime.primeFactors hp']
684 simp
685
686/-! ### Totient as cardinality -/
687