A365655 Number of fixed n-polyominoids, allowing right-angled connections only ("hard" polyominoids).

3, 12, 68, 438, 3054, 22417, 170610, 1334316

Offset: 1

Author

Pontus von Brömssen, Sep 17 2023

Keywords

• nonn
• hard
• more

Comments

Apparently, the definition of "hard" polyominoid in the Wikipedia article differs from the definition used here. Here, two squares are allowed to meet in a straight 180-degree connection provided that the structure be connected through right-angled ("hard") connections only; see A365654 for further details.

Links

• Wikipedia, Polyominoid.
• Index entries for sequences related to polyominoes.

Crossrefs

Cf. A075678 (polyominoids), A365654 (free).

13th and 17th row of A366767.