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A145807 1/2 the number of islands of ones fitting in an n X n array symmetric under 180 degree rotation with all ones connected only either two adjacent vertically or two adjacent horizontally. 0

%I

%S 0,0,1,2,3,4,6,8,9,12,14,18,20,23,27,32

%N 1/2 the number of islands of ones fitting in an n X n array symmetric under 180 degree rotation with all ones connected only either two adjacent vertically or two adjacent horizontally.

%e 8 X 8 example with 16 islands

%e .0.1.0.1.0.1.0.1

%e .0.1.0.1.0.1.0.1

%e .1.0.1.0.1.0.1.0

%e .1.0.1.0.1.0.1.0

%e .0.1.0.1.0.1.0.1

%e .0.1.0.1.0.1.0.1

%e .1.0.1.0.1.0.1.0

%e .1.0.1.0.1.0.1.0

%K nonn

%O 1,4

%A _R. H. Hardin_, Oct 19 2008

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Last modified June 19 00:04 EDT 2021. Contains 345125 sequences. (Running on oeis4.)