Hook length inequalities for $t$-regular partitions in the $t$-aspect

Abstract

Let $t\ge 2$ and $k\ge 1$ be integers. A $t$-regular partition of a positive integer $n$ is a partition of $n$ such that none of its parts is divisible by $t$. Let $b_{t,k}(n)$ denote the number of hooks of length $k$ in all the $t$-regular partitions of $n$. In this article, we prove some inequalities for $b_{t,k}(n)$ for fixed values of $k$. We prove that for any $t\ge 2$, $b_{t+1,1}(n)\ge b_{t,1}(n)$, for all $n\ge 0$. We also prove that $b_{3,2}(n)\ge b_{2,2}(n)$ for all $n>3$, and $b_{3,3}(n)\ge b_{2,3}(n)$ for all $n\ge 0$. Finally, we state some problems for future works.

To appear in Canadian Mathematical Bulletin