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A269013
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Number of 3 X n binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two exactly once.
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1
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0, 15, 46, 305, 1078, 4948, 18210, 73277, 270458, 1026795, 3757996, 13847240, 50155940, 181596651, 651546278, 2331910405, 8300115170, 29460799452, 104176325510, 367430075801, 1292287850546, 4534933300095, 15878737307224
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OFFSET
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1,2
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LINKS
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FORMULA
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Empirical: a(n) = 4*a(n-1) + 8*a(n-2) - 34*a(n-3) - 16*a(n-4) + 60*a(n-5) - 25*a(n-6).
Empirical g.f.: x^2*(15 - 14*x + x^2) / (1 - 2*x - 6*x^2 + 5*x^3)^2. - Colin Barker, Jan 18 2019
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EXAMPLE
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Some solutions for n=4:
..1..1..0..1. .0..0..0..0. .1..0..0..0. .1..0..0..0. .0..1..0..1
..0..0..0..0. .1..1..0..0. .0..0..0..0. .1..0..1..0. .1..0..0..0
..1..0..0..0. .0..0..0..1. .1..1..0..0. .1..0..0..1. .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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