Rigged Horse Numbers and their Modular Periodicity
Benjamin Schreyer
Departments of Computer Science and Physics
University of Maryland
College Park, MD 20742
USA
and
Plasma Physics Division
U.S. Naval Research Laboratory
Washington, D.C. 20375
USA
Abstract:
The Fubini numbers count the permutations of horse racing where ties
are possible. The closely related r-horse numbers count the finishes of
a horse race where some subset of r horses agree to finish the race in
a specific relative strong ordering. We express the r-Fubini numbers as
a sum of r index-shifted sequences of Fubini numbers weighted with the
signed Stirling numbers of the first kind. We use a novel shift operator
counting argument. Further, we demonstrate the eventual modular periodicity of
r-Fubini numbers. Their maximum period is determined to be the Carmichael
function of the modulus. The maximum period occurs in the case of an
odd modulus for Fubini numbers.
Full version: pdf,
dvi,
ps,
latex
(Concerned with sequences
A000670
A002322
A008275
A008277
A232473
A232474.)
Received August 2 2024; revised versions received August 3 2024; August 19 2024; November
27 2024; November 29 2024.
Published in Journal of Integer Sequences,
July 31 2025.
Return to
Journal of Integer Sequences home page