Tenreiro Machado, José AntónioGalhano, AlexandraCao Labora, Daniel2021-02-122021-02-122021Mathematics 2021, 9(4), 314; https://doi.org/10.3390/math9040314http://hdl.handle.net/10347/24434This manuscript focuses on one of the most famous open problems in mathematics, namely the Collatz conjecture. The first part of the paper is devoted to describe the problem, providing a historical introduction to it, as well as giving some intuitive arguments of why is it hard from the mathematical point of view. The second part is dedicated to the visualization of behaviors of the Collatz iteration function and the analysis of the resultseng© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)Atribución 4.0 Internacionalhttp://creativecommons.org/licenses/by/4.0/Multidimensional scalingCollatz conjectureClustering methodsjournal article10.3390/math90403142227-7390open access