lean_workbook_plus_36275

Proved

by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

Calculate $a_1$ for the sequence $a_n=\sqrt{n(n+1)}$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_36275 (a : ℕ → ℝ) (a_def : ∀ n, a n = Real.sqrt (n * (n + 1))) : a 1 = Real.sqrt 2   :=  by sorry

Source