

A234012


Number of unbiased free polyominoes with 2n squares.


2




OFFSET

1,2


COMMENTS

Define the bias of a polyomino to be the difference between the number of black squares and the number of white squares when chessboard coloring is applied to the polyomino. Unbiased polyominoes are those having an equal number of black and white squares. The sequence is defined for 2n rather than n as oddsized polyominoes are obviously biased.


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CROSSREFS



KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



