OPEN
This is open, and cannot be resolved with a finite computation.
If\[n! = \prod_i p_i^{k_i}\]is the factorisation into distinct primes then let $h(n)$ count the number of distinct exponents $k_i$.
Prove that there exists some $c>0$ such that\[h(n) \sim c \left(\frac{n}{\log n}\right)^{1/2}\]as $n\to \infty$.
A problem of Erdős and Selfridge, who proved (see
[Er82c])\[h(n) \asymp \left(\frac{n}{\log n}\right)^{1/2}.\]A heuristic of Tao using the Cramér model for the primes (detailed in the comments) suggests this is true with\[c=\sqrt{2\pi}=2.506\cdots.\]
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T. F. Bloom, Erdős Problem #912, https://www.erdosproblems.com/912, accessed 2026-01-16