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A140989
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Half the number of n X n binary matrices, symmetric about both diagonal and antidiagonal, having equal row sums.
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0
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1, 2, 3, 12, 19, 173, 447, 8068, 36753, 1320227, 10915053, 783176689, 11979427593, 1712476502823, 48833478632641, 13961837241242892, 750837577374124089
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listen;
history;
text;
internal format)
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OFFSET
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1,2
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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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