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A269105
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Number of nX4 0..3 arrays with some element plus some horizontally or vertically adjacent neighbor totalling three no more than once.
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1
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216, 15540, 872460, 43964700, 2085484068, 95166487524, 4227147007836, 184069947098892, 7894012975085748, 334480929126425748, 14034341507370527532, 584107408947764887164, 24145251769444080595908
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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) = 90*a(n-1) -2559*a(n-2) +24556*a(n-3) -94959*a(n-4) +140442*a(n-5) -69169*a(n-6) for n>7
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EXAMPLE
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Some solutions for n=2
..3..2..0..2. .3..1..1..0. .2..3..1..3. .3..0..0..2. .0..0..2..3
..2..0..0..1. .2..0..3..1. .2..2..3..3. .3..1..0..0. .0..0..3..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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