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A232923
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Number of 4 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally, diagonally or antidiagonally.
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1
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81, 162, 1122, 5808, 33702, 186720, 1054446, 5907444, 33206862, 186398988, 1046931522, 5878727460, 33013750890, 185390166264, 1041086668026, 5846332684128, 32830815650766, 184365298149288, 1035325615443174
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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) = 3*a(n-1) + 16*a(n-2) - 3*a(n-3) - 25*a(n-4) + 2*a(n-5) + 4*a(n-6) for n>7.
Empirical g.f.: 3*x*(27 - 27*x - 220*x^2 + 31*x^3 + 279*x^4 - 20*x^5 - 40*x^6) / (1 - 3*x - 16*x^2 + 3*x^3 + 25*x^4 - 2*x^5 - 4*x^6). - Colin Barker, Oct 06 2018
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EXAMPLE
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Some solutions for n=5:
..1..0..1..2..2....2..2..1..2..1....0..0..0..1..0....1..2..1..2..1
..1..0..1..2..2....2..2..2..2..1....0..0..0..0..0....1..0..1..0..1
..1..2..1..2..1....2..1..2..2..1....0..0..0..0..0....0..0..0..0..0
..1..0..1..2..2....0..1..2..2..1....1..0..1..0..1....0..0..0..1..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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