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A230185
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Number of 2 X n 0..2 arrays x(i,j) with each element horizontally or antidiagonally next to at least one element with value 2-x(i,j).
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1
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0, 9, 27, 159, 825, 4395, 23307, 123729, 656715, 3485775, 18502017, 98206299, 521266155, 2766812505, 14685878427, 77950719519, 413752211145, 2196142553835, 11656837079787, 61872964697889, 328413594039435, 1743176349744015
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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) + 7*a(n-2) + a(n-3) - 6*a(n-4) - 5*a(n-5) for n>6.
Empirical g.f.: 3*x^2*(3 - 3*x - 4*x^2 - 3*x^3 + 3*x^4) / ((1 - x)*(1 + x)*(1 - 4*x - 6*x^2 - 5*x^3)). - Colin Barker, Sep 21 2018
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EXAMPLE
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Some solutions for n=3:
..2..0..2....0..2..0....1..1..2....1..1..2....0..2..1....1..1..1....0..2..2
..2..0..2....0..1..1....1..0..2....2..0..2....0..1..1....1..0..2....2..0..2
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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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