Journal of Integer Sequences, Vol. 26 (2023), Article 23.8.4

Arithmetic Functions that Remain Constant on Runs of Consecutive Integers


Noah Lebowitz-Lockard and Joseph Vandehey
Department of Mathematics
University of Texas at Tyler
Tyler, TX 75799
USA

Abstract:

We bound from above the length of the longest sequence of consecutive numbers less than or equal to x with the same number of divisors. We also bound the length of the longest sequence of consecutive numbers less than or equal to x for which the number of divisors is decreasing. Finally, we consider variants of this problem such as the corresponding sequences for the sum-of-proper-divisors function and the Carmichael function. In particular, we show that it is impossible for the sum-of-proper-divisors function to be equal on six consecutive integers.


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(Concerned with sequence A006558.)


Received February 24 2023; revised versions received April 13 2023; September 12 2023. Published in Journal of Integer Sequences, October 3 2023.


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