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A270114
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Number of nX4 0..7 arrays with some element plus some horizontally or vertically adjacent neighbor totalling seven exactly once.
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1
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1176, 6183744, 16972694928, 38799000374400, 81224231406183600, 161437591343857507392, 310047482243688075320784, 581128015182716709115556736, 1069573733021300551214375558640
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 3378*a(n-1) -3070271*a(n-2) +370787212*a(n-3) -17482148143*a(n-4) +363880874050*a(n-5) -2797694462161*a(n-6) for n>7
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EXAMPLE
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Some solutions for n=1
..6..1..3..0. .1..2..6..1. .7..0..1..3. .6..2..4..3. .5..2..3..5
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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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