Identically vanishing $k$-generalized Fibonacci polynomials

Fuente: arXiv
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Autore principale: Mane, S. R.
Natura: Preprint
Pubblicazione: 2025
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author Mane, S. R.
author_facet Mane, S. R.
contents The recurrence for the $k$-Fibonacci polynomials is usually iterated upwards to positive values of $n$ only. When the recurrence is iterated downwards to $n<0$, there are indices where the polynomials vanish identically. This fact does not seem to have been noted in the literature. We derive the set of such indices. We establish the connection of our results to the solution of the Skolem problem for the $k$-Fibonacci numbers. For $k\ge3$ and $n<0$, we show that the degree of the polynomial does not increase monotonically with $|n|$. The so-called `left-justified $k$-nomial triangle' is extended to treat negative indices. We derive expressions for the individual polynomial coefficients (the elementary symmetric polynomials of the roots). We present results for the properties of the polynomials, for both $n>0$ and $n<0$, including factorization of the polynomials and properties of the roots. Results are also derived for real roots. We present new, tighter, bounds on the amplitudes of the nonzero roots. We derive new combinatorial sums for the polynomial coefficients, which are more concise and computationally efficient than previously published expressions.
format Preprint
id arxiv_https___arxiv_org_abs_2507_11596
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Identically vanishing $k$-generalized Fibonacci polynomials
Mane, S. R.
Combinatorics
11B39, 11B37, 05A15
The recurrence for the $k$-Fibonacci polynomials is usually iterated upwards to positive values of $n$ only. When the recurrence is iterated downwards to $n<0$, there are indices where the polynomials vanish identically. This fact does not seem to have been noted in the literature. We derive the set of such indices. We establish the connection of our results to the solution of the Skolem problem for the $k$-Fibonacci numbers. For $k\ge3$ and $n<0$, we show that the degree of the polynomial does not increase monotonically with $|n|$. The so-called `left-justified $k$-nomial triangle' is extended to treat negative indices. We derive expressions for the individual polynomial coefficients (the elementary symmetric polynomials of the roots). We present results for the properties of the polynomials, for both $n>0$ and $n<0$, including factorization of the polynomials and properties of the roots. Results are also derived for real roots. We present new, tighter, bounds on the amplitudes of the nonzero roots. We derive new combinatorial sums for the polynomial coefficients, which are more concise and computationally efficient than previously published expressions.
title Identically vanishing $k$-generalized Fibonacci polynomials
topic Combinatorics
11B39, 11B37, 05A15
url https://arxiv.org/abs/2507.11596