Automatic Enumeration of Tilings by Polyominoes

We revisit Zeilberger's computational framework for enumerating polyomino tilings and demonstrate its use in counting tilings of $k\times n$ boards by $L$-tetrominoes, allowing rotations. Recently, B\v{e}lohoubek and Slav\'ik gave a generating function for tilings of $2n\times 4$ boards by $L$-tetrominoes. Motivated by their work, we first verify the method by automatically recovering their generating function. We then apply the method to widths $5$ through $9$ and obtain explicit rational generating functions and new integer sequences that are not currently listed in the OEIS.