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arXiv · 2604.25051

Families of Eliahou semigroups linked to Farey intervals

Axel Bacher
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Abstract

We describe a way to explore the numerical semigroup tree to find all Eliahou semigroups of conductor up to 200 (and conjecturally up to 400) thanks to a new way of representing the semigroups and pruning off unwanted branches. This proves that Wilf's conjecture holds for conductor up to 200. Based on this list, we describe new classes of numerical semigroups, with a Farey interval as a crucial parameter. We show that these semigroups probably all satisfy Wilf's conjecture. We explicitly construct many families of Eliahou semigroups belonging to these classes, encompassing families described by Delgado, Eliahou and Fromentin, and Bras-Amor\'os.

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Axel Bacher. 2026-04-27. Families of Eliahou semigroups linked to Farey intervals. https://arxiv.org/abs/2604.25051

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