Erdős Problem 367

### What is the conjecture

https://www.erdosproblems.com/367

Let $B_2(n)$ be the 2-full part of $n$ (that is, $B_2(n)=n/n'$ where $n'$ is the product of all primes that divide $n$ exactly once). Is it true that, for every fixed $k\geq 1$,
$$\prod_{n\leq m

Start by reading the conjecture statement in this issue and the linked Erdős Problems page, then inspect the existing formalized conjectures in the repository to identify the relevant entry point and conventions. Done means adding a Lean formalization of Erdős Problem 367 that matches the stated conjecture and fits the repository's existing structure.

Written by the indexing model from the issue text.