English

Legendre's formula and $p$-adic analysis

Number Theory 2019-07-30 v1 Combinatorics

Abstract

In number theory, we know Legendre's formula vp(n!)=k1npk v_p(n!) = \sum_{k \ge 1} \lfloor \frac{n}{p^k} \rfloor , which calculates the pp-adic valuation of the factorial, i.e. the exponent of the greatest power of a prime pp that divides n!n!. There is also the second (or alternative) equality vp(n!)=nsp(n)p1 v_p (n!) = \frac{n-s_p(n)}{p-1} where sp(n)s_p(n) is the pp-adic weight of nn or the sum of digits of nn in base pp. Both kinds of Legendre's formula allow us to determine valuations of the natural number, the odd factorial, binomial coefficients, Catalan numbers, and other combinatorial objects. The article examines the relationship between the pp-adic valuation and pp-adic weight and considers their increments. The arithmetic of the pp-adic increments is proposed.

Keywords

Cite

@article{arxiv.1907.11902,
  title  = {Legendre's formula and $p$-adic analysis},
  author = {Gennady Eremin},
  journal= {arXiv preprint arXiv:1907.11902},
  year   = {2019}
}

Comments

10 pages

R2 v1 2026-06-23T10:32:39.052Z