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A140217
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Half the number of n X n binary matrices, symmetric under horizontal reflection, having equal row sums.
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1
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1, 1, 2, 9, 34, 730, 4376, 905345, 10601986, 10009765626, 200097656252, 2177748514672962, 85812416258106784, 4142789042980129347156, 289904403212517959978240, 175519033940460517461369847809
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OFFSET
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1,3
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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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