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A183444
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Number of n X 3 binary arrays with every 1 having exactly two king-move neighbors equal to 1.
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2
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1, 9, 18, 30, 107, 265, 553, 1505, 3852, 8922, 22477, 56889, 137617, 340401, 851098, 2091618, 5160851, 12817517, 31655009, 78159377, 193558964, 478614470, 1182673261, 2925763109, 7235864705, 17887850273, 44237338898, 109401520982
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OFFSET
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1,2
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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) - a(n-2) + 8*a(n-3) - 7*a(n-4) + 2*a(n-5) - 2*a(n-6).
Empirical g.f.: x*(1 + 7*x + x^2 - 5*x^3 - 2*x^5) / (1 - 2*x + x^2 - 8*x^3 + 7*x^4 - 2*x^5 + 2*x^6). - Colin Barker, Feb 27 2018
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EXAMPLE
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Some solutions for 5 X 3:
..0..1..0....1..1..0....0..0..0....0..0..0....1..1..0....0..0..0....0..0..1
..0..1..1....1..0..0....0..1..1....0..1..0....0..1..0....0..0..0....0..1..1
..0..0..0....0..0..0....0..0..1....1..0..1....0..0..0....0..0..0....0..0..0
..0..1..0....0..1..1....1..0..0....1..0..1....1..0..0....1..1..0....1..0..0
..1..1..0....0..0..1....1..1..0....0..1..0....1..1..0....1..0..0....1..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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