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A297853
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Number of n X 3 0..1 arrays with every element equal to 1, 2 or 4 king-move adjacent elements, with upper left element zero.
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2
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1, 7, 15, 19, 21, 33, 53, 77, 111, 171, 269, 415, 643, 1013, 1605, 2543, 4041, 6451, 10325, 16547, 26561, 42705, 68741, 110743, 178545, 288053, 464971, 750861, 1212959, 1960023, 3167961, 5121325, 8280457, 13390095, 21655079, 35024669
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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-4) - a(n-5) - a(n-6) + a(n-7) + a(n-8) for n>9.
Empirical g.f.: x*(1 + 5*x + x^2 - 11*x^3 - 16*x^4 - x^5 + 10*x^6 + 11*x^7 + 4*x^8) / ((1 - x)*(1 + x^2)*(1 - x - x^2)*(1 - x^2 - x^3)). - Colin Barker, Mar 22 2018
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EXAMPLE
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Some solutions for n=7:
..0..0..1. .0..1..0. .0..1..1. .0..1..0. .0..1..0. .0..0..1. .0..0..1
..1..0..1. .1..0..1. .0..0..1. .0..1..0. .1..0..1. .1..1..1. .0..1..1
..0..1..0. .0..1..0. .1..1..1. .0..1..0. .1..0..0. .1..0..0. .0..0..0
..1..1..0. .0..1..1. .1..0..0. .0..1..0. .1..0..0. .1..1..1. .1..1..0
..1..1..0. .0..1..1. .1..1..0. .0..1..0. .1..0..1. .0..0..1. .0..0..0
..0..1..0. .0..1..0. .0..0..0. .0..1..0. .0..1..0. .1..1..1. .0..1..1
..1..0..1. .1..0..1. .0..1..1. .0..1..0. .1..0..1. .1..0..0. .0..0..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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