OFFSET
1,2
COMMENTS
This sequence and the related sequences A365650-A365655 and A365996-A366010 count polyominoids (A075679) with different rules for how the cells can be connected. In these sequences, connections other than the specified ones are permitted, but the polyominoids must be connected through the specified connections only. The polyominoids counted by this sequence, for example, are allowed to have right-angled corner-connections and flat edge-connections, as long as they are not needed for the polyominoid to be connected. A connection is flat if the two neighboring cells lie in the same plane, otherwise it is right-angled.
LINKS
Pontus von Brömssen, Illustration for sizes 1..3.
Wikipedia, Polyominoid.
CROSSREFS
Cf. A365996 (fixed).
21st row of A366766.
The following table lists counting sequences for free, fixed, and one-sided polyominoids with different sets of allowed connections. "|" means flat connections and "L" means right-angled connections.
corner-connections | edge-connections | free | fixed | 1-sided
-------------------+------------------+---------+---------+--------
KEYWORD
nonn,hard,more
AUTHOR
Pontus von Brömssen, Sep 26 2023
STATUS
approved