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%I #24 Aug 22 2020 15:53:55
%S 1,4,24,230,2601,32810,433855,5923677,82675193,1173878266
%N Number of unbiased free polyominoes with 2n squares.
%C 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 odd-sized polyominoes are obviously biased.
%H Herman Tulleken, <a href="https://www.researchgate.net/publication/333296614_Polyominoes">Polyominoes 2.2: How they fit together</a>, (2019).
%Y Cf. A000105, A001933.
%K nonn,more
%O 1,2
%A _John Mason_, Dec 18 2013
%E a(9)-a(10) from _Sean A. Irvine_, Aug 22 2020
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