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A208254
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Number of n X 4 0..2 arrays with new values 0..2 introduced in row major order and no element equal to more than one of its immediate leftward or upward neighbors.
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1
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14, 768, 43344, 2445264, 137947632, 7782199824, 439026252912, 24767296501776, 1397226183866736, 78823339024454928, 4446752320207192176, 250859789016717819408, 14152043831975777230704, 798375640062491402594064
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 61*a(n-1) - 266*a(n-2) + 416*a(n-3) - 256*a(n-4) for n>5.
Empirical g.f.: 2*x*(7 - 43*x + 110*x^2 - 128*x^3 + 64*x^4) / (1 - 61*x + 266*x^2 - 416*x^3 + 256*x^4). - Colin Barker, Jun 29 2018
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EXAMPLE
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Some solutions for n=4
..0..0..0..0....0..0..0..1....0..0..1..2....0..1..0..2....0..0..0..0
..1..0..1..0....2..0..1..0....0..2..2..0....1..2..2..1....1..2..2..2
..2..1..0..1....0..2..1..1....2..0..0..1....1..0..1..2....1..2..1..1
..2..0..1..0....2..0..0..1....2..1..2..1....0..1..2..0....1..2..1..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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