On a Sequence Related to the Factoradic Representation of an Integer
Maximiliano Sánchez Garza
Facultad de Ciencias Físico Matemáticas
Universidad Autónoma de Nuevo León
Av. Universidad
Ciudad Universitaria
San Nicolás de los Garza, Nuevo León 66451
México
Enrique Treviño
Mathematics Department
Lake Forest College
555 N. Sheridan Road
Lake Forest, IL 60045
USA
Abstract:
For a positive integer r, define jr
to be the smallest positive integer
n satisfying n! > nr–1.
In this paper we prove jr+1 ∈
{jr + 1, jr + 2},
which leads us to explore the set of positive integers r for
which jr+1 = jr + 2.
We prove this set has the same density as the prime
numbers. The sequence jr
was introduced by Carlson, Goedhart, and Harris
in their work on factoradic happy numbers, and we prove some properties
of jr
that lead to an improvement of one of their theorems.
Full version: pdf,
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(Concerned with sequences
A007770
A027641
A230319
A336803.)
Received January 26 2021; revised versions received January 27 2021; July 20 2021.
Published in Journal of Integer Sequences,
August 17 2021.
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