OFFSET
1,8
COMMENTS
A polyomino is 'kissing' if there exist two cells that touch only at a corner such that no cell exists touching both edgewise simultaneously.
The sequence differs from A359520 (Number of free holey polyominoes of n cells with simply-connected interiors) at a(12) because of:
OOOO OOO
O O O O OO
OOOOO OO O
OOO
which are kissing (and hence holey) but do not have simply-connected interiors.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
John Mason, Sep 25 2024
STATUS
approved