Problem 404

Erdős Problem #404: declared status 'open'. Formalized: no. For which integers $a\geq 1$ and primes $p$ is there a finite upper bound on those $k$ such that there are $a=a_1<\cdots<a_n$ with$$p^k \mid (a_1!+\cdots+a_n!)?$$If $f(a,p)$ is the greatest such $k$, how does this function behave? Is there a prime $p$ and an infinite sequence $a_1<a_2<\cdots$ such that if $p^{m_k}$ is the highest power of $p$ dividing $\sum_{i\leq k}a_i!$ then $m_k\to \infty$? Prize: no. Tags: factorials, number theory.