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A217340
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Number of n X 2 arrays of occupancy after each element moves to some horizontal or vertical neighbor but without 2-loops
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6
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0, 1, 7, 38, 190, 918, 4367, 20623, 97052, 455960, 2140404, 10043697, 47120343, 221046178, 1036902766, 4863888050, 22815211759, 107019570351, 501996648392, 2354712588592, 11045229346424, 51809744028497, 243023401329015
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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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FORMULA
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Empirical: a(n) = 7*a(n-1) -11*a(n-2) +a(n-3) -a(n-4).
Empirical g.f.: x^2 / (1 - 7*x + 11*x^2 - x^3 + x^4). - Colin Barker, Feb 18 2018
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EXAMPLE
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All solutions for n=3:
..0..0....1..1....1..1....1..1....1..0....0..1....1..1
..2..2....1..2....2..1....2..2....2..1....1..2....1..1
..1..1....0..1....1..0....0..0....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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