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A301994
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Number of nX3 0..1 arrays with every element equal to 1, 2 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.
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1
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1, 2, 5, 15, 48, 155, 499, 1602, 5137, 16467, 52784, 169199, 542375, 1738618, 5573261, 17865479, 57269040, 183579891, 588478091, 1886407378, 6047009817, 19384109803, 62137109808, 199184819687, 638500768991, 2046758546378, 6561026627701
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OFFSET
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1,2
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COMMENTS
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Column 3 of A301999.
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..210
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FORMULA
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Empirical: a(n) = 5*a(n-1) -7*a(n-2) +4*a(n-3)
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EXAMPLE
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Some solutions for n=5
..0..0..0. .0..0..1. .0..0..1. .0..0..1. .0..0..1. .0..0..0. .0..0..1
..1..1..0. .1..1..0. .1..1..1. .0..1..1. .1..1..1. .1..1..0. .1..1..1
..1..0..0. .0..0..0. .1..0..0. .0..0..1. .1..1..1. .0..0..0. .1..0..0
..1..1..0. .0..1..1. .1..1..0. .0..1..0. .1..0..0. .0..1..0. .1..1..1
..1..0..0. .1..0..0. .1..0..0. .1..0..0. .0..1..1. .1..0..0. .0..0..0
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CROSSREFS
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Cf. A301999.
Sequence in context: A149925 A149926 A321467 * A289589 A071739 A268407
Adjacent sequences: A301991 A301992 A301993 * A301995 A301996 A301997
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Mar 30 2018
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STATUS
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approved
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