Multiplicative independence in the sequence of $k$-generalized Pell numbers

TL;DR

This paper characterizes all pairs of terms in the $k$-generalized Pell sequence that are multiplicatively dependent, explicitly listing the small solutions and employing advanced number theory techniques.

Contribution

It provides a complete classification of multiplicative dependence among sequence terms, extending understanding of generalized Pell numbers.

Findings

Only small $k,m,n$ yield multiplicative dependence

Explicit solutions are listed for all such pairs

The proof combines linear forms in logarithms and computational methods

Abstract

We study multiplicative dependence between terms of the $k$-generalized Pell sequence $(P_n^{(k)})_{n\ge 2-k}$, defined by the linear recurrence \[ P_n^{(k)} = 2P_{n-1}^{(k)} + P_{n-2}^{(k)} + \dots + P_{n-k}^{(k)}, \] with initial conditions $P_0^{(k)} = \dots = P_{-(k-2)}^{(k)} = 0$ and $P_1^{(k)} = 1$. For $k\ge 2$ we determine all pairs $(m,n)$ with $n>m\ge 0$ such that $P_n^{(k)}$ and $P_m^{(k)}$ are multiplicatively dependent. The main result states that the only solutions occur for very small $k,m,n$ (which are listed explicitly). The proof uses lower bounds for linear forms in logarithms (Matveev), the Baker-Davenport reduction algorithm, and a computational search.