Theorem: Finset.sum_shift_back (PrimeNumberTheoremAnd/Wiener.lean)

State before:
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✝¹ : _root_.RCLike 𝕜
E : Type u_1
inst✝ : Ring E
u : ℕ → E
n : ℕ
⊢ cumsum u (n + 1) = cumsum u n + u n
Tactic:
simp [cumsum, Finset.range_succ, add_comm]
State after:
no goals