Second-order asymptotics for distinct factors of n! above n

Let f(n) be the smallest possible largest factor in a factorization n!=a₁⋯aₖ with distinct integers n<a₁<⋯<aₖ. What is the second-order growth of f(n) beyond 2n?

Why it matters and what counts as progress

Why it matters: The second-order term distinguishes factorizations with the same leading 2n scale and asks for a sharp construction.

What counts as progress: Match upper and lower bounds for (f(n)−2n)log n/n or determine its limiting constant.

How the problem developed

  1. 1982 · Partial result [1]

    Paul Erdős, Richard K. Guy and John L. Selfridge Established the order of growth f(n)−2n≈n/log n for the least possible largest distinct factor in a factorization of n! into factors exceeding n.

  2. 3 May 2026 · Lower bound [2]

    Mausberg Reported the thirteen-layer lower-bound constant later appearing in the claimed limit, without a matching upper bound or asymptotic formula.

  3. 28 Jul 2026 · Proof claim [3]

    Shouqiao Wang A manuscript claims that (f(n)−2n)log(n)/n tends to 4029639598/25970038185, adding a matching upper-bound construction.

AI contribution

A Proposed Solution to Erdős Problem 390

Shouqiao Wang

For the least possible largest distinct factor f(n) in n! = a₁⋯aₖ with n<a₁<⋯<aₖ, Wang’s manuscript claims that (f(n)−2n)log(n)/n tends to 4029639598/25970038185. Its new step is a matching upper-bound construction.

AI involvementAI-led
ImportanceNotable
Human understandingFew
Reported

Sources

  1. Erdős Problem #390
  2. Mausberg’s earlier lower-bound note
  3. Wang, Erdős #390 asymptotic manuscript
  4. Lean statement of the upper-bound endpoint
  5. Successful Lean CI run
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