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A141512
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Number of n X n binary matrices, symmetric about the diagonal and under 90-degree rotation, with no more than 3 ones in any 2 X 2 subblock.
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1
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1, 2, 1, 7, 4, 49, 21, 648, 245, 16475, 5184, 801489, 214175, 74700792, 16831269, 13333992705, 2539826928, 4558747755857, 733369598775, 2985167883475040, 405728550271273, 3743977846899435969, 429864175220405760
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OFFSET
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0,2
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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