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A064050
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Number of essentially different (not mappable to each other by reflection or rotation) arrangements of numbers 1 to n*(n+1)/2 in a triangle of n rows, in such a way that each row and each diagonal is increasing or decreasing.
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2
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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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more,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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