rw [(by rw [div_mul]; simp : 1 / (2 * π) = 1 / (2 * π * I) * I), mul_assoc]
case neg.e_a
ψ : ℝ → ℝ
diffΨ : ContDiff ℝ 1 ψ
ψpos : ∀ (x : ℝ), 0 ≤ ψ x
suppΨ : support ψ ⊆ Icc (1 / 2) 2
mass_one : ∫ (x : ℝ) in Ioi 0, ψ x / x = 1
X : ℝ
X_pos : 0 < X
ε : ℝ
εpos : 0 < ε
n : ℕ
n_zero : ¬n = 0
n_pos : 0 < n
⊢ 1 / (2 * ↑π) * ∫ (t : ℝ), mellin (fun x => ↑(Smooth1 ψ ε x)) (2 + ↑t * I) * (↑n / ↑X) ^ (-(2 + ↑t * I)) =
    ↑(Smooth1 ψ ε (↑n / X))
case neg.e_a
ψ : ℝ → ℝ
diffΨ : ContDiff ℝ 1 ψ
ψpos : ∀ (x : ℝ), 0 ≤ ψ x
suppΨ : support ψ ⊆ Icc (1 / 2) 2
mass_one : ∫ (x : ℝ) in Ioi 0, ψ x / x = 1
X : ℝ
X_pos : 0 < X
ε : ℝ
εpos : 0 < ε
n : ℕ
n_zero : ¬n = 0
n_pos : 0 < n
⊢ 1 / (2 * ↑π * I) * (I * ∫ (t : ℝ), mellin (fun x => ↑(Smooth1 ψ ε x)) (2 + ↑t * I) * (↑n / ↑X) ^ (-(2 + ↑t * I))) =
    ↑(Smooth1 ψ ε (↑n / X))