On Modular Representations of C-Recursive Integer Sequences
M. Prunescu
University of Bucharest
Research Center for Logic, Optimization and Security (LOS)
Faculty of Mathematics and Computer Science
Academiei 14
Bucharest (RO-010014)
Romania
and
Institute of Logic and Data Science
Bucharest
Romania
and
Simion Stoilow Institute of Mathematics of the Romanian Academy
Research Unit 5
P. O. Box 1-764
Bucharest (RO-014700)
Romania
J. M. Shunia
Independent Researcher
Ann Arbor, MI
USA
Abstract:
Prunescu and Sauras-Altuzarra showed that all C-recursive sequences of
natural numbers have an arithmetic div-mod representation that can be
derived from their generating function. This representation consists
of computing the quotient of two exponential polynomials and taking the
remainder of the result modulo a third exponential polynomial, and works
for all integers n ≥ 1. Using a diļ¬erent approach, Prunescu proved
the existence of two other representations, one of which is the mod-mod
representation, consisting of two successive remainder computations. This
result has two weaknesses: the representation works only ultimately, and
a correction term must be added to the first exponential polynomial. We
show that a mod-mod representation without inner correction term
holds for all integers n ≥ 1. This follows directly from the div-mod
representation by an arithmetic short-cut from outside.
Full version: pdf,
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(Concerned with sequences
A000032
A000045
A000051
A000073
A000129
A000225
A000930
A000931
A001080
A001081
A001477
A002203
A002249
A007395
A088137.)
Received March 11 2025; revised versions received March 12 2025; September 16 2025.
Published in Journal of Integer Sequences,
September 16 2025.
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