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A225344
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Number of nX8 -1,1 arrays such that the sum over i=1..n,j=1..8 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 8-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship)
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1
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1, 1, 5, 27, 171, 1081, 7261, 50659, 364051, 2676331, 20044255, 152452967, 1174757541, 9154016699, 72023900129, 571498084391, 4568690484153, 36765944370729, 297627015600415, 2422216988266317, 19808260648181603
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OFFSET
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1,3
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COMMENTS
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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...-1.-1.-1.-1..1..1..1..1...-1.-1.-1.-1.-1.-1..1..1
.-1.-1..1..1..1..1..1..1...-1.-1.-1.-1.-1.-1..1..1...-1.-1..1..1..1..1..1..1
.-1.-1.-1.-1.-1.-1.-1.-1....1..1..1..1..1..1..1..1...-1.-1..1..1..1..1..1..1
.-1.-1..1..1..1..1..1..1...-1.-1.-1.-1.-1.-1..1..1...-1.-1.-1.-1.-1.-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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