On $7^k$-regular partitions modulo powers of $7$

In this study, we explore the arithmetic properties of $b_{7^k}(n)$ for any $k\ge 1$, which enumerates the partitions of $n$ where no part is divisible by $7^k$. By constructing generating functions for $b_{7^k}(n)$ over specific arithmetic progressions, we establish a collection of Ramanujan-type congruences.