Greatest Common Divisors of Shifted Fibonacci Sequences Revisited
Annalena Rahn and Martin Kreh
Institute of Mathematics and Applied Computer Science
University of Hildesheim
Samelsonplatz 1
31141 Hildesheim
Germany
Abstract:
In 2011, Chen computed the greatest common divisors of consecutive
shifted Fibonacci numbers Fn + a and
Fn+1 + a for a ∈ {±1,
±2}. He also showed that gcd(Fn + a,
Fn+1 + a) is bounded if a ≠ ±1.
This was later generalized by Spilker, who also showed that
gcd(Fn + a,
Fn+1 + a) is
periodic if a ≠ ±1. In this article, we compute the
greatest common divisor for a = ±3 and we show how the
results given in this article compare to bounds derived by Chen and
periods derived by Spilker. We further give a necessary criterion for
an integer d to occur as such a greatest common divisor.
Full version: pdf,
dvi,
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latex
(Concerned with sequence
A000045.)
Received January 31 2018; revised version received June 20 2018.
Published in Journal of Integer Sequences, August 22 2018.
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