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A305581
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Number of nX3 0..1 arrays with every element unequal to 0, 1, 2, 7 or 8 king-move adjacent elements, with upper left element zero.
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1
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4, 3, 6, 8, 19, 33, 60, 112, 205, 377, 694, 1276, 2347, 4317, 7940, 14604, 26861, 49405, 90870, 167136, 307411, 565417, 1039964, 1912792, 3518173, 6470929, 11901894, 21890996, 40263819, 74056709, 136211524, 250532052, 460800285, 847543861
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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) = a(n-1) +a(n-2) +a(n-3) for n>5
Empirical: f(x)= -(2*x^4-5*x^3-x^2-x+4)*x/(x^3+x^2+x-1). - Simon Plouffe, Jun 20 2018
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EXAMPLE
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Some solutions for n=5
..0..0..0. .0..1..1. .0..0..1. .0..0..0. .0..1..1. .0..0..1. .0..0..1
..0..1..0. .1..0..1. .0..1..0. .0..0..0. .1..0..1. .0..1..0. .0..1..0
..0..0..0. .1..1..1. .0..0..0. .0..0..0. .1..1..1. .0..0..0. .0..0..0
..0..0..0. .1..0..1. .0..1..0. .0..1..0. .1..1..1. .0..1..0. .0..1..0
..0..0..0. .1..1..1. .0..0..1. .0..0..0. .1..1..1. .1..0..0. .0..0..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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