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A269048
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Number of n X 4 0..2 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once.
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1
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60, 360, 3078, 24192, 183072, 1350672, 9779808, 69793968, 492374976, 3441051984, 23861339424, 164375084016, 1125975740544, 7675458754704, 52099028628960, 352309891913520, 2374503933353280, 15956129491021776, 106934858162261664
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 14*a(n-1) - 57*a(n-2) + 56*a(n-3) - 16*a(n-4) for n>5.
Empirical g.f.: 6*x*(10 - 80*x + 243*x^2 - 290*x^3 + 105*x^4) / (1 - 7*x + 4*x^2)^2. - Colin Barker, Jan 18 2019
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EXAMPLE
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Some solutions for n=4:
..0..1..2..0. .2..1..2..1. .1..2..1..2. .0..0..0..1. .2..1..1..2
..0..1..0..1. .2..1..0..1. .1..2..1..2. .0..0..0..0. .2..2..2..2
..0..0..0..0. .2..1..2..0. .2..2..2..2. .0..0..0..1. .2..2..2..1
..0..1..0..0. .2..1..0..1. .1..1..2..1. .1..0..0..0. .2..1..2..1
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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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