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A268793
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Number of nX3 0..2 arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two exactly once.
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1
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12, 78, 248, 950, 3384, 11948, 41248, 140698, 474472, 1586038, 5262024, 17348096, 56884272, 185647624, 603388088, 1953997896, 6307338900, 20300666174, 65169102416, 208712267048, 666993883320, 2127375490930, 6773070493400
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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) = 2*a(n-1) +9*a(n-2) -2*a(n-3) -33*a(n-4) -42*a(n-5) -14*a(n-6) +10*a(n-7) +8*a(n-8) -a(n-10) for n>12
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EXAMPLE
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Some solutions for n=4
..2..2..1. .0..1..2. .0..0..0. .1..0..1. .1..0..0. .2..2..2. .2..1..0
..1..2..2. .1..2..2. .1..0..1. .0..1..0. .0..0..1. .2..2..2. .1..0..1
..1..2..1. .2..2..2. .0..1..0. .0..0..1. .0..0..2. .1..2..1. .0..0..0
..2..2..2. .2..2..1. .0..0..0. .1..0..0. .0..1..2. .2..1..0. .0..1..0
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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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