Remarks on a certain restricted partition function of Lin (2503.23996v1)

Abstract: Let $b(n)$ be the number of three-colored partitions $\pi=(\pi_1,\pi_2,\pi_3)$ of $n$ such that $\pi_1$ has distinct odd parts and $\pi_2$ and $\pi_3$ have parts only divisible by $4$. Utilizing modular forms, Lin obtained the generating functions for $b(3n+1)$ and $b(3n+2)$, which yields the congruence $b(3n+2)\equiv 0\pmod{3}$. In this work, we give elementary proofs of these generating functions by employing $q$-series manipulations and dissection formulas. We also establish an infinite family of internal congruences modulo $3$ satisfied by $b(n)$.