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A269091
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Number of n X 2 0..3 arrays with some element plus some horizontally or vertically adjacent neighbor totalling three exactly once.
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2
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4, 96, 1152, 11424, 103488, 889056, 7375872, 59698464, 474360768, 3715826016, 28777886592, 220814937504, 1681292682048, 12718165610976, 95670977133312, 716203564928544, 5338972029467328, 39651633731043936, 293513242790716032
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OFFSET
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1,1
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COMMENTS
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Column 2 of A269097.
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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) = 14*a(n-1) -49*a(n-2) for n>3.
Conjectures from Colin Barker, Mar 21 2018: (Start)
G.f.: 4*x*(1 + 10*x + x^2) / (1 - 7*x)^2.
a(n) = 96*7^(n-3)*(5*n-3) for n>1.
(End)
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EXAMPLE
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Some solutions for n=4:
..2..0. .2..2. .3..3. .3..3. .1..3. .3..3. .2..2. .3..2. .3..3. .1..3
..1..1. .2..2. .2..3. .2..2. .3..1. .0..1. .3..2. .2..3. .3..3. .0..1
..1..1. .1..0. .3..1. .1..3. .2..2. .1..0. .1..0. .0..1. .1..0. .0..2
..3..3. .3..2. .2..2. .3..3. .3..3. .0..1. .1..2. .0..2. .3..2. .2..2
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CROSSREFS
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Cf. A269097.
Sequence in context: A359653 A202682 A089639 * A204973 A204700 A267953
Adjacent sequences: A269088 A269089 A269090 * A269092 A269093 A269094
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Feb 19 2016
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STATUS
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approved
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