Problem Statement
For any $k\geq 2$ let $g_k(n)$ denote the maximum value of\[(a_1+\cdots+a_k)-n\]where $a_1,\ldots,a_k$ are integers such that $a_1!\cdots a_k! \mid n!$. Can one show that\[\sum_{n\leq x}g_k(n) \sim c_k x\log x\]for some constant $c_k$? Is it true that there is a constant $c_k$ such that for almost all $n<x$ we have\[g_k(n)=c_k\log x+o(\log x)?\]
Categories:
Number Theory Factorials
Progress
Erdős and Graham write that it is easy to show that $g_k(n) \ll_k \log n$ always, but the best possible constant is unknown.See also [401].
Source: erdosproblems.com/400 | Last verified: January 14, 2026