The Comma Sequence: A Simple Sequence With Bizarre Properties
Number Theory
2024-05-28 v2
Abstract
The ``comma sequence'' starts with 1 and is defined by the property that if k and k' are consecutive terms, the two-digit number formed from the last digit of k and the first digit of k' is equal to the difference k'-k. If there is more than one such k', choose the smallest, but if there is no such k' the sequence terminates. The sequence begins 1, 12, 35, 94, 135, ... and, surprisingly, ends at term 2137453, which is 99999945. The paper analyzes the sequence and its generalizations to other starting values and other bases. A slight change in the rules allows infinitely long comma sequences to exist.
Cite
@article{arxiv.2401.14346,
title = {The Comma Sequence: A Simple Sequence With Bizarre Properties},
author = {Eric Angelini and Michael S. Branicky and Giovanni Resta and N. J. A. Sloane and David W. Wilson},
journal= {arXiv preprint arXiv:2401.14346},
year = {2024}
}
Comments
19 pages, 4 figures, 1 table. Corrected a formula, expanded discussion of an asymptotic estimate, other small changes