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

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

Offset

1,1

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

Table of n, a(n) for n=1..8.

Wikipedia, Polyominoid.

Index entries for sequences related to polyominoes.

Crossrefs

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

13th and 17th row of A366767.

Sequence in context: A187118 A121812 A039750 * A366228 A296979 A004127

Adjacent sequences: A365652 A365653 A365654 * A365656 A365657 A365658

Keyword

nonn,hard,more

Author

Pontus von Brömssen, Sep 17 2023

Status

approved