have := calc
  (n+2) % 2
    = n%2 := Nat.add_mod_right ..
  _ = 1 := hodd
n : Nat
h_ind :
  ∀ {i : Nat},
    getBit (Nat.lsb (n / 2 + 1)) i = true ↔
      getBit (n / 2 + 1) i = true ∧ ∀ (j : Nat), j < i → getBit (n / 2 + 1) j = false
i : Nat
hodd : n % 2 = 1
⊢ getBit (Nat.lsb (n + 2)) (succ i) = true ↔
    getBit (n + 2) (succ i) = true ∧ ∀ (j : Nat), j < succ i → getBit (n + 2) j = false
n : Nat
h_ind :
  ∀ {i : Nat},
    getBit (Nat.lsb (n / 2 + 1)) i = true ↔
      getBit (n / 2 + 1) i = true ∧ ∀ (j : Nat), j < i → getBit (n / 2 + 1) j = false
i : Nat
hodd : n % 2 = 1
this : (n + 2) % 2 = 1
⊢ getBit (Nat.lsb (n + 2)) (succ i) = true ↔
    getBit (n + 2) (succ i) = true ∧ ∀ (j : Nat), j < succ i → getBit (n + 2) j = false