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A183354
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One quarter the number of nX2 1..4 arrays with no two neighbors of any element equal to each other
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1
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4, 36, 144, 576, 2304, 9216, 36864, 147456, 589824, 2359296, 9437184, 37748736, 150994944, 603979776, 2415919104, 9663676416, 38654705664, 154618822656, 618475290624, 2473901162496, 9895604649984, 39582418599936, 158329674399744
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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)=4*a(n-1) = A002063(n-1) for n>2
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EXAMPLE
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Some solutions for 5X2 with a(1,1)=1
..1..1....1..3....1..2....1..3....1..3....1..2....1..4....1..2....1..3....1..3
..4..2....4..2....4..4....4..4....4..2....1..2....3..3....4..3....2..2....4..3
..3..3....4..2....3..3....3..2....4..1....4..4....2..2....2..1....4..1....4..2
..1..1....3..1....1..1....1..2....2..3....2..3....1..1....2..1....4..1....3..2
..2..4....2..1....2..2....1..3....1..3....1..1....4..4....3..4....2..3....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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