Beck-type companion identities for Franklin's identity

Abstract

In 2017, Beck conjectured that the difference in the number of parts in all partitions of $n$ into odd parts and the number of parts in all strict partitions of $n$ is equal to the number of partitions of $n$ whose set of even parts has one element, and also to the number of partitions of $n$ with exactly one part repeated. Andrews proved the conjecture using generating functions. Beck's identity is a companion identity to Euler's identity. The theorem has been generalized (with a combinatorial proof) by Yang to a companion identity to Glaisher's identity. Franklin generalized Glaisher's identity, and in this article, we provide a Beck-type companion identity to Franklin's identity and prove it both analytically and combinatorially. Andrews' and Yang's respective theorems fit naturally into this very general frame. We also discuss how Franklin's identity and the companion Beck-type identities can be further generalized to Euler pairs of any order.