

A131482


a(n) is the number of ncelled polyominoes with perimeter 2n+2.


9



1, 1, 2, 4, 11, 27, 83, 255, 847, 2829, 9734, 33724, 118245, 416816, 1478602, 5267171, 18840144, 67611472, 243378415, 878407170, 3178068821, 11523323634, 41865833602, 152382134767
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OFFSET

1,3


COMMENTS

2n+2 is the maximal perimeter of an ncelled polyomino. a(n) is the number of ncelled polyominoes that have a tree as their connectedness graph (vertices of this graph correspond to cells and two vertices are connected if the corresponding cells have a common edge).


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FORMULA



CROSSREFS

A359522 counts only polyominoes with holes.
A002013 counts only unbranched polyominoes.
A038142 is the analog for polyhexes.


KEYWORD

hard,more,nonn


AUTHOR



EXTENSIONS



STATUS

approved



