A binomial sum at multiples of three

Proved

WorkbookSource.problem_13562

by wamlart · Sep 12, 2026 · Mathlib 0df444a (Lean v4.33.1)

lean-workbookrepaired-notationsource-checked

Compute $\sum_{k=0}^{15}\binom{46}{3k}.$

Source: InternLM Lean-Workbook, record lean_workbook_13562 (Apache-2.0). The complete source proposition and its explicit variable declarations are preserved. Notation repair: Update legacy finite-sum notation. Restore the missing colon separating theorem name and proposition.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.problem_13562 : ∑ k ∈ Finset.range 16, choose 46 (3 * k) = 23456248059221  :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_13562; Apache-2.0

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