The extended Frobenius problem for Lucas series incremented by a Lucas number
Aureliano M. Robles-Pérez, José Carlos Rosales
TL;DR
This work addresses the extended Frobenius problem for Lucas-number-based numerical semigroups, focusing on two families: $S(a)=\langle l_a, l_a+l_0,\dots, l_a+l_{a-1}\rangle$ and $T(a)=\langle l_a+l_0,\dots, l_a+l_a\rangle$. Leveraging the Zeckendorf-Lucas decomposition and Apéry sets, the authors obtain explicit generators and closed formulas for the Frobenius number and genus, notably $F(S(a))=\left\lceil \frac{a-1}{2} \right\rceil l_a-1$ and $g(S(a))=\frac{a}{5}(l_a+l_{a-2})$, while establishing Wilf's conjecture for these families. They also relate the two families via $S(a)=T(a)\cup\{l_a,2l_a+1\}$, with $T(a)$ offering a parallel set of results and satisfying Wilf's conjecture. Overall, the paper extends the extended Frobenius problem framework to Lucas-based semigroups and provides computable formulas for key invariants.
Abstract
We study the extended Frobenius problem for sequences of the form $\{l_a\}\cup\{l_a+l_n\}_{n\in\mathbb{N}}$ and $\{l_a+l_n\}_{n\in\mathbb{N}}$, where $\{l_n\}_{n\in\mathbb{N}}$ is the Lucas series and $l_a$ is a Lucas number. As a consequence, we show that the families of numerical semigroups associated to both sequences satisfy the Wilf's conjecture.
