lean_workbook_plus_30940

Proved

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

Find the number of ways to climb an $n-$ step staircase if you can only take $1$ or $2$ stairs at a time.

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_30940 (n : ℕ) : ∃ F : ℕ → ℕ, F 0 = 1 ∧ F 1 = 2 ∧ F (n + 2) = F (n + 1) + F n   :=  by sorry

Source