Counting numbers divisible by neither five nor seven

Proved

WorkbookSource.problem_20899

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

lean-workbookrepaired-notationsource-checked

p4. How many whole numbers, from $1$ to $2006$ , are divisible neither by $5$ nor by $7$ ?

Source: InternLM Lean-Workbook, record lean_workbook_20899 (Apache-2.0). The complete source proposition and its explicit variable declarations are preserved. Notation repair: Update legacy finite-sum notation.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.problem_20899 : ∑ i ∈ Finset.filter (λ x => ¬ (5∣x) ∧ ¬ (7∣x)) (Finset.Icc 1 2006), 1 = 1376  :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_20899; Apache-2.0

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