have l9 : ∀ᶠ n in atTop, u (n + 1) ≤ u n := by filter_upwards [l7, l8] with n l2 l8 ; dsimp [u] ; gcongr <;> simp
n : ℕ
A a b c d u✝ x y t σ' : ℝ
ψ Ψ : ℝ → ℂ
F G : ℂ → ℂ
f : ℕ → ℂ
𝕜 : Type
inst✝ : _root_.RCLike 𝕜
u : ℕ → ℝ := fun n => (↑n * (↑n).log ^ 2)⁻¹
l7 : ∀ᶠ (n : ℕ) in atTop, 1 ≤ (↑n).log
l8 : ∀ᶠ (n : ℕ) in atTop, 1 ≤ n
⊢ Summable fun n => (↑n * (↑n).log ^ 2)⁻¹
n : ℕ
A a b c d u✝ x y t σ' : ℝ
ψ Ψ : ℝ → ℂ
F G : ℂ → ℂ
f : ℕ → ℂ
𝕜 : Type
inst✝ : _root_.RCLike 𝕜
u : ℕ → ℝ := fun n => (↑n * (↑n).log ^ 2)⁻¹
l7 : ∀ᶠ (n : ℕ) in atTop, 1 ≤ (↑n).log
l8 : ∀ᶠ (n : ℕ) in atTop, 1 ≤ n
l9 : ∀ᶠ (n : ℕ) in atTop, u (n + 1) ≤ u n
⊢ Summable fun n => (↑n * (↑n).log ^ 2)⁻¹