On $\boldsymbolψ$-amicable numbers and their generalizations
S. I. Dimitrov
TL;DR
This work studies the distribution of $\psi$-amicable numbers arising from Dedekind's $\psi$-function, proving that the set of such pairs has zero asymptotic density by adapting Erdős’ method to the multiplicative $\psi$-function. It develops a general framework for $\psi$-amicable $k$-tuples, including a constructive criterion that yields $aN_1,\dots,aN_k$ as a $\psi$-amicable tuple when coprimality and ratio conditions hold. Additionally, it presents an alternative definition of $\psi$-amicable $k$-tuples and catalogs extensive explicit examples for triples, quadruples, quintuples, and sextuples, linking to relevant OEIS sequences. Overall, the paper extends amicable-type phenomena from the divisor-sum function to Dedekind’s $\psi$, demonstrating sparsity while providing systematic construction approaches and rich tabulated instances.
Abstract
In this article, we study the properties of $ψ$-amicable numbers. We prove that their asymptotic density relative to the positive integers is zero. We also propose generalizations of $ψ$-amicable numbers.
