Легкое чтение для профессионалов
On the least common multiple of several consecutive values of a polynomial
A. Dubickas Institute of Mathematics, Faculty of Mathematics and Informatics, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania
Аннотация:
In this note we prove the periodicity of an arithmetic function that is the quotient of the product of
$k+1$ values (where
$k \geq 1$) of a polynomial
$f \in {\mathbb Z}[x]$ at
$k + 1$ consecutive integers
${f(n) f(n + 1) \cdots f(n + k)}$ and the least common multiple of the corresponding integers
${f(n),f(n + 1),\dots,f(n + k)}$. We show that this function is periodic if and only if no difference between two roots of
$f$ is a positive integer smaller than or equal to
$k$. This implies an asymptotic formula for the least common multiple of
$f(n),f(n+1),\dots,f(n+k)$ and extends some earlier results in this area from linear and quadratic polynomials
$f$ to polynomials of arbitrary degree
$d$. A period in terms of the reduced resultants of
$f(x)$ and
$f(x+\ell)$, where
$1 \leq \ell \leq k$, is given explicitly, as well as few examples of
$f$ when the smallest period can be established.
Ключевые слова:
least common multiple, reduced resultant, periodic arithmetic function.
Поступила в редакцию: 13.10.2019
Язык публикации: английский