The Maximum Length for Ducci Sequences on $\mathbb{}Z_m^n$ when $n$ is Even

TL;DR

This paper investigates the maximum length of Ducci sequences over _m^n when n is even, providing an upper bound for the time until the sequence enters a cycle.

Contribution

It establishes an upper bound on the length of Ducci sequences in _m^n for even n, advancing understanding of their cyclical behavior.

Findings

Derived an explicit upper bound for sequence length

Proved the bound holds for all even n

Enhanced understanding of Ducci sequence dynamics

Abstract

Let $D: \mathbb{Z}_m^n \to \mathbb{Z}_m^n$ be defined so \[D(x_1, x_2, ..., x_n)=(x_1+x_2 \; \text{mod} \; m, x_2+x_3 \; \text{mod} \; m, ..., x_n+x_1 \; \text{mod} \; m).\] $D$ is known as the Ducci function and for $\mathbf{u} \in \mathbb{Z}_m^n$, $\{D^{\alpha}(\mathbf{u})\}_{\alpha=0}^{\infty}$ is the Ducci sequence of $\mathbf{u}$. Every Ducci sequence enters a cycle because $\mathbb{Z}_m^n$ is finite. In this paper, we aim to establish an upper bound for how long it will take for a Ducci sequence in $\mathbb{Z}_m^n$ to enter its cycle when $n$ is even.