数学理论与应用 ›› 2022, Vol. 42 ›› Issue (1): 85-91.

• • 上一篇    下一篇

一些二项式系数的最大公因数

肖嘉琪,袁平之*,林序灿   

  1. 华南师范大学数学科学学院,广州, 510631
  • 出版日期:2022-03-31 发布日期:2022-03-23

The Greatest Common Divisor of Certain Set of Binomial Coefficients

Xiao Jiaqi, Yuan Pingzhi*, Lin Xucan   

  1. School of Mathematical Science, South China Normal University, Guangzhou 510631, China
  • Online:2022-03-31 Published:2022-03-23
  • Contact: Pingzhi Yuan(1966-), Professor, PhD, E-mail: yuanpz@scnu.edu.cn
  • Supported by:
    This work is supported by National Natural Science Foundation of China (No. 12171163)

摘要:

本文证明: 若$n\geq4$和$a\ge 0$为整数且满足$a<\frac{n}{3}$, 则

$$\gcd\left(\left\{\binom{n}{k}:a<k<n-a\right\}\right)=\prod_{n=p^{m}+b(n,p),\ 0\le b(n,p)\leq a,} p,$$ 其中 $\binom{n}{k}=\frac{n!}{k!(n-k)!}$, 右边的连乘积遍历所有满足$ n=p^{m}+b(n,p), m\in\mathbb{N}$ 和 $0\le b(n,p)\leq a$ 的素数 $p$.

作为上述结论的一个应用,我们回答洪[16]文中的一个问题.

关键词: 二项式系数 , 最大公因数

Abstract:

In this paper, we prove that if $n\geq4$ and $a\ge 0$ are integers satisfying $a<\frac{n}{3}$, then

$$\gcd\left(\left\{\binom{n}{k}:a<k<n-a\right\}\right)=\prod_{n=p^{m}+b(n,p),\ 0\le b(n,p)\leq a,} p,$$ where $\binom{n}{k}=\frac{n!}{k!(n-k)!}$, and the product in the right hand side runs through all primes $p$ such that $ n=p^{m}+b(n,p), m\in\mathbb{N}$ and $0\le b(n,p)\leq a$.

As an application of our result, we give an answer to a problem in Hong [16].


Key words: Binomial coefficient , Greatest common divisor