Theorem: HurwitzZeta.sinZeta_two_mul_nat_add_one'
File: Mathlib/NumberTheory/LSeries/HurwitzZetaValues.lean

Proof steps:
state_before: k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
⊢ sinZeta (↑x) (2 * ↑k + 1) =
    (-1) ^ (k + 1) / (2 * ↑k + 1) / (2 * ↑k + 1).Gammaℂ *
      Polynomial.eval (↑x) (Polynomial.map (algebraMap ℚ ℂ) (Polynomial.bernoulli (2 * k + 1)))
state_after: k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
⊢ (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / 2 / ↑(2 * k + 1)! *
      Polynomial.eval (↑x) (Polynomial.map (algebraMap ℚ ℂ) (Polynomial.bernoulli (2 * k + 1))) =
    (-1) ^ (k + 1) / (2 * ↑k + 1) / (2 * ↑k + 1).Gammaℂ *
      Polynomial.eval (↑x) (Polynomial.map (algebraMap ℚ ℂ) (Polynomial.bernoulli (2 * k + 1)))
tactic: rw [sinZeta_two_mul_nat_add_one hk hx]
state_before: k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
⊢ (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / 2 / ↑(2 * k + 1)! *
      Polynomial.eval (↑x) (Polynomial.map (algebraMap ℚ ℂ) (Polynomial.bernoulli (2 * k + 1))) =
    (-1) ^ (k + 1) / (2 * ↑k + 1) / (2 * ↑k + 1).Gammaℂ *
      Polynomial.eval (↑x) (Polynomial.map (algebraMap ℚ ℂ) (Polynomial.bernoulli (2 * k + 1)))
state_after: case e_a
k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
⊢ (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / 2 / ↑(2 * k + 1)! = (-1) ^ (k + 1) / (2 * ↑k + 1) / (2 * ↑k + 1).Gammaℂ
tactic: congr 1
state_before: case e_a
k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
⊢ (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / 2 / ↑(2 * k + 1)! = (-1) ^ (k + 1) / (2 * ↑k + 1) / (2 * ↑k + 1).Gammaℂ
state_after: case e_a
k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
this : ↑(2 * k + 1)! = (2 * ↑k + 1) * Complex.Gamma (2 * ↑k + 1)
⊢ (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / 2 / ↑(2 * k + 1)! = (-1) ^ (k + 1) / (2 * ↑k + 1) / (2 * ↑k + 1).Gammaℂ
tactic: have : (2 * k + 1)! = (2 * k + 1) * Complex.Gamma (2 * k + 1) := by
    rw [(by simp : Complex.Gamma (2 * k + 1) = Complex.Gamma (↑(2 * k) + 1)),
       Complex.Gamma_nat_eq_factorial, ← Nat.cast_ofNat (R := ℂ), ← Nat.cast_mul,
      ← Nat.cast_add_one, ← Nat.cast_mul, ← Nat.factorial_succ]
state_before: case e_a
k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
this : ↑(2 * k + 1)! = (2 * ↑k + 1) * Complex.Gamma (2 * ↑k + 1)
⊢ (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / 2 / ↑(2 * k + 1)! = (-1) ^ (k + 1) / (2 * ↑k + 1) / (2 * ↑k + 1).Gammaℂ
state_after: case e_a
k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
this : ↑(2 * k + 1)! = (2 * ↑k + 1) * Complex.Gamma (2 * ↑k + 1)
⊢ (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / (2 * (2 * ↑k + 1) * Complex.Gamma (2 * ↑k + 1)) =
    (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * ↑k + 1) / ((2 * ↑k + 1) * 2 * Complex.Gamma (2 * ↑k + 1))
tactic: simp_rw [this, Gammaℂ, cpow_neg, ← div_div, div_inv_eq_mul, div_mul_eq_mul_div, div_div]
state_before: case e_a
k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
this : ↑(2 * k + 1)! = (2 * ↑k + 1) * Complex.Gamma (2 * ↑k + 1)
⊢ (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / (2 * (2 * ↑k + 1) * Complex.Gamma (2 * ↑k + 1)) =
    (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * ↑k + 1) / ((2 * ↑k + 1) * 2 * Complex.Gamma (2 * ↑k + 1))
state_after: case e_a
k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
this : ↑(2 * k + 1)! = (2 * ↑k + 1) * Complex.Gamma (2 * ↑k + 1)
⊢ (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / (2 * ↑(2 * k + 1) * Complex.Gamma ↑(2 * k + 1)) =
    (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / (↑(2 * k + 1) * 2 * Complex.Gamma ↑(2 * k + 1))
tactic: rw [(by simp : 2 * (k : ℂ) + 1 = ↑(2 * k + 1)), cpow_natCast]
state_before: case e_a
k : ℕ
x : ℝ
hk : k ≠ 0
hx : x ∈ Icc 0 1
this : ↑(2 * k + 1)! = (2 * ↑k + 1) * Complex.Gamma (2 * ↑k + 1)
⊢ (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / (2 * ↑(2 * k + 1) * Complex.Gamma ↑(2 * k + 1)) =
    (-1) ^ (k + 1) * (2 * ↑π) ^ (2 * k + 1) / (↑(2 * k + 1) * 2 * Complex.Gamma ↑(2 * k + 1))
state_after: no goals
tactic: ring