A Note On Certain Minimal Excludants Over Overpartitions

Source abstract

Let $σ\mathrm{Mex}(n)$ and $σ_e\mathrm{Mex}(n)$ denote the sum of minimal excludants and sum of even minimal excludants over all overpartitions respectively. In this work, we study these two combinatorial objects from an arithmetic perspective. We prove that, for $n\geq 0$, $σ_e\mathrm{Mex}(n)\equivσ\mathrm{Mex}(n)-\bar{p}_{\geq 2}(n)\pmod{2^2},$ where $\bar{p}_{\geq 2}(n)$ denotes the number of overpartitions of $n$ with all parts at least $2$. Furthermore, we prove the asymptotic behavior of $σ\mathrm{Mex}(n)$, $σ_e\mathrm{Mex}(n)$, and $\bar{p}_{\geq 2}(n)$ as $n\to\infty$. In particular, we prove that $σ\mathrm{Mex}(n)\sim 2\,σ_e\mathrm{Mex}(n).$