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A233021
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Number of n X 3 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally, vertically, diagonally or antidiagonally, and top left element zero.
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1
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9, 81, 849, 8835, 92067, 959385, 9997413, 104179551, 1085618895, 11312857317, 117887355777, 1228463178219, 12801387988827, 133398816787089, 1390102724464989, 14485777543658775, 150951255149241255
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OFFSET
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1,1
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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) = 11*a(n-1) - 5*a(n-2) - 11*a(n-3) + 2*a(n-4).
Empirical g.f.: 3*x*(3 - 6*x + x^2) / (1 - 11*x + 5*x^2 + 11*x^3 - 2*x^4). - Colin Barker, Oct 07 2018
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EXAMPLE
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Some solutions for n=5:
..0..1..0....0..0..1....0..0..0....0..1..0....0..1..3....0..0..0....0..1..0
..0..1..1....1..1..1....2..2..2....1..1..0....0..1..1....0..2..0....0..1..1
..0..1..0....3..3..3....3..2..0....1..0..0....1..1..1....2..0..2....1..1..1
..1..1..1....1..1..1....3..2..2....0..0..0....1..3..3....2..0..2....1..3..3
..1..0..0....3..3..1....2..2..2....0..0..2....1..1..1....2..2..2....3..3..2
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CROSSREFS
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Column 3 of A233026.
Sequence in context: A001514 A077364 A077486 * A187122 A113361 A180737
Adjacent sequences: A233018 A233019 A233020 * A233022 A233023 A233024
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Dec 03 2013
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STATUS
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approved
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