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A331649
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Number of binary matrices with n distinct columns and any number of distinct nonzero rows with 2 ones in every column and columns in decreasing lexicographic order.
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2
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1, 0, 3, 17, 230, 3264, 60338, 1287062, 31900620, 893284155, 27972470286, 967596779631, 36654913572018, 1509052435744560, 67089897326522970, 3203343744126663616, 163486870943294124046, 8881542959996746368420, 511713241494851800728865, 31165957861936237845310435
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OFFSET
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0,3
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COMMENTS
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The condition that the columns be in decreasing order is equivalent to considering nonequivalent matrices with distinct columns up to permutation of columns.
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LINKS
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EXAMPLE
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The a(2) = 3 matrices are:
[1 1] [1 0] [1 0]
[1 0] [1 1] [0 1]
[0 1] [0 1] [1 1]
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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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