Prove2Me

Elementary arithmetic identity #28191

Proved
WorkbookCorrected.plus_28191

by carlok · Sep 29, 2026 · Mathlib 0df444a (Lean v4.33.1)

arithmeticcorrectedelementaryworkbook

The elementary natural-number / rational identity

1+6+15+20+15+6+1=641 + 6 + 15 + 20 + 15 + 6 + 1 = 64

holds by direct arithmetic evaluation.

Formalization Note: This corrects Lean-Workbook record lean_workbook_plus_28191, which omitted a compilable colon/type annotation and/or used a preamble of only Mathlib.Analysis.Complex.Basic.

Source: InternLM Lean-Workbook, record lean_workbook_plus_28191 (Apache-2.0).

Preamble
import Mathlib.Tactic.NormNum
Formal statement
theorem WorkbookCorrected.plus_28191 : 1 + 6 + 15 + 20 + 15 + 6 + 1 = 64 := by sorry
Source
https://huggingface.co/datasets/internlm/Lean-Workbook; record lean_workbook_plus_28191; Apache-2.0; corrects Open node 61d342d2-ed2a-49c9-b5da-1c7097420916

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