
COMMENTS

The sequence gives the number of distinct tilings by polyominoes of a square with side n. As for "free" polyominoes, tilings that are reflections or rotations of each other are not considered distinct.
Using the same terminology used for polyominoes: the corresponding sequence for "fixed" tilings is 1,12,1434,1691690, and for onesided tilings is 1,5,222,213315.
