OFFSET
0,2
COMMENTS
This sequence counts "free" polyforms where holes are allowed. This means that two polyforms are considered the same if one is a rigid transformation (translation, rotation, reflection or glide reflection) of the other.
a(n) >= A343417(n), the number of (n-k)-polyominoes with k distinguished vertices.
LINKS
Peter Kagey, Haskell program for computing sequence.
John Mason, Illustration of equivalence between truncated square polyforms and a mixture of crosses and squares.
Wikipedia, Truncated Square Tiling
CROSSREFS
Analogous for other tilings: A000105 (square), A000228 (hexagonal), A000577 (triangular), A197156 (prismatic pentagonal), A197159 (floret pentagonal), A197459 (rhombille), A197462 (kisrhombille), A197465 (tetrakis square), A309159 (snub square), A343398 (trihexagonal), A343406 (truncated hexagonal).
KEYWORD
nonn,more
AUTHOR
Peter Kagey, Apr 20 2021
EXTENSIONS
a(11) from Drake Thomas, May 02 2021
a(12)-a(16) from John Mason, Mar 20 2022
STATUS
approved