English

On a problem of Chen and Liu concerning the prime power factorization of $n!$

Number Theory 2011-10-24 v1

Abstract

For a fixed prime pp, let ep(n!)e_p(n!) denote the order of pp in the prime factorization of n!n!. Chen and Liu (2007) asked whether for any fixed mm, one has {ep(n2!)modm:  nZ}=Zm\{e_p(n^2!) \bmod m:\; n\in\mathbb{Z}\}=\mathbb{Z}_m and {ep(q!)modm:  qprime}=Zm\{e_p(q!) \bmod m:\; q {prime}\}=\mathbb{Z}_m. We answer these two questions and show asymptotic formulas for # \{n<x: n \equiv a \bmod d,\; e_p(n^2!)\equiv r \bmod m\} and # \{q<x: q {prime}, q \equiv a \bmod d,\; e_p(q!)\equiv r \bmod m\}. Furthermore, we show that for each h3h\geq 3, we have {n<x:namodd,  ep(nh!)rmodm}x4/(3h+1)\{n<x: n \equiv a \bmod d,\; e_p(n^h!)\equiv r \bmod m\} \gg x^{4/(3h+1)}.

Keywords

Cite

@article{arxiv.1110.4814,
  title  = {On a problem of Chen and Liu concerning the prime power factorization of $n!$},
  author = {Johannes F. Morgenbesser and T. Stoll},
  journal= {arXiv preprint arXiv:1110.4814},
  year   = {2011}
}

Comments

9 pages