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A195640
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Number of lower triangles of an n X n 0..4 array with all row sums equal to the length of the row and all column sums equal to the length of the column.
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1
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1, 1, 3, 19, 391, 25428, 5422820, 3868544673, 9374373474455, 78121590505558308, 2262375741577763676620, 229653423345084153764141412, 82310438395814327559991274396712, 104810153877236566878585186368604425875
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OFFSET
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1,3
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LINKS
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EXAMPLE
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Some solutions for n=4:
..1........1........1........1........1........1........1........1
..2.0......0.2......1.1......0.2......0.2......0.2......1.1......2.0
..1.0.2....1.0.2....1.0.2....1.0.2....3.0.0....3.0.0....1.0.2....1.0.2
..0.3.0.1..2.1.0.1..1.2.0.1..2.1.0.1..0.1.2.1..0.1.2.1..1.2.0.1..0.3.0.1
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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