

A342537


Number of free polyominoes with n cells having simplyconnected interiors.


4



1, 1, 2, 5, 12, 35, 108, 368, 1283, 4639, 17003, 63222, 236819, 893515, 3387953, 12904855, 49335965, 189243115
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OFFSET

1,3


COMMENTS

The polyominoes referred to in the definition are those having a single traceable perimeter. The definition therefore includes the heptomino with a hole, as in this case the border, although not selfavoiding (it meets itself at a corner) is still traceable; it excludes the square octomino with a hole, whose border consists of two distinct polygons. Thus starting from n=8, A000104(n) < a(n) < A000105(n).


LINKS



CROSSREFS

Cf. A000104 (free polyominoes without holes), A000105 (free polyominoes).


KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



