OFFSET
2,3
COMMENTS
A polyomino for which more than one closed path exists counts as 1. On the other hand, in A266549, distinct closed paths count separately. For example for n=7, this latter sequence distinguishes between
+-+ +-+
| | | |
+ +-+ +-+
| |
+-+-+-+-+
and
+-+-+-+
| |
+ +-+ +-+
| | | |
+-+ +-+-+
LINKS
John Mason, Examples
EXAMPLE
For n = 4 the a(4) = 3 solutions are:
XXX XX XXXX
X X XXX XXXX
XXX XXX
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
John Mason and Tanya Khovanova, Mar 07 2023
EXTENSIONS
a(13) - a(16) from Bert Dobbelaere, Mar 09 2023
STATUS
approved