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A302000
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Number of 3Xn 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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0, 5, 5, 26, 84, 309, 1108, 3979, 14314, 51440, 185083, 665473, 2393298, 8606453, 30950505, 111303112, 400265922, 1439423515, 5176415456, 18615274437, 66943726862, 240741120250, 865746384343, 3113372499381, 11196221683404
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OFFSET
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1,2
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COMMENTS
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Row 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) = 2*a(n-1) +6*a(n-2) -2*a(n-4) +2*a(n-5) -9*a(n-6) -50*a(n-7) -37*a(n-8) +34*a(n-9) +43*a(n-10) -16*a(n-11) +15*a(n-12) +18*a(n-13) -7*a(n-14) -2*a(n-16) +4*a(n-17) -6*a(n-18) +a(n-20)
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EXAMPLE
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Some solutions for n=5
..0..0..1..1..1. .0..0..0..1..1. .0..0..1..1..1. .0..0..0..1..1
..0..0..0..0..1. .1..1..1..0..1. .0..1..0..0..0. .1..1..0..1..1
..1..1..0..1..1. .0..0..0..1..1. .1..1..1..1..1. .1..0..0..1..1
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CROSSREFS
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Cf. A301999.
Sequence in context: A203191 A165423 A220078 * A219351 A130220 A081847
Adjacent sequences: A301997 A301998 A301999 * A302001 A302002 A302003
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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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