Lean4
theorem minFacHelper_1 {n k k' : ℕ} (e : k + 2 = k') (h : MinFacHelper n k) (np : minFac n ≠ k) : MinFacHelper n k' :=
by
rw [← e]
refine ⟨Nat.lt_add_right _ h.1, ?_, ?_⟩
· rw [add_mod, mod_self, add_zero, mod_mod]
exact h.2.1
rcases h.2.2.eq_or_lt with rfl | h2
· exact (np rfl).elim
rcases (succ_le_of_lt h2).eq_or_lt with h2 | h2
· refine ((h.1.trans_le h.2.2).ne ?_).elim
have h3 : 2 ∣ minFac n := by rw [Nat.dvd_iff_mod_eq_zero, ← h2, succ_eq_add_one, add_mod, h.2.1]
rw [dvd_prime <| minFac_prime h.one_lt.ne'] at h3
norm_num at h3
exact h3
exact h2