A Note on Non-Integrality of the (k, l)-Göbel Sequences
Yuh Kobayashi
Faculty of Information Design
Heisei International University
Mizubuka Odateno 2000
Kazo, Saitama 347-8504
Japan
Shin-ichiro Seki
Nagahama Institute of Bio-Science and Technology
Tamura 1266
Nagahama, Shiga, 526-0829
Japan
Abstract:
The (k, l)-Göbel sequences defined by Ibstedt remain
integers for the first (in some cases, many) terms, but for selected
values of (k, l) computations show that the terms eventually
stop being integers. It is still unresolved whether the integrality
of these sequences breaks down for all k, l ≥ 2.
In this article, we prove the non-integrality for a specific class of
(k, l) values. Our proof is based on geometric arguments
related to the distribution of quadratic residues modulo a prime.
Full version: pdf,
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(Concerned with sequences
A003504
A108394.)
Received
December 23 2024; revised versions received June 2 2026; June 3 2026.
Published in Journal of Integer Sequences,
June 4 2026.
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