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A208859
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Number of n X 3 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or left-upward diagonal neighbors.
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1
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5, 127, 5796, 273049, 12883280, 607924387, 28686344276, 1353633375649, 63874412830520, 3014066220322507, 142225889552418956, 6711267165754821049, 316687117317930292160, 14943635501046735026227, 705151014286332805949636
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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) = 59*a(n-1) - 603*a(n-2) + 2211*a(n-3) - 2826*a(n-4) + 720*a(n-5) for n>6.
Empirical g.f.: x*(5 - 168*x + 1318*x^2 - 3389*x^3 + 1710*x^4 - 240*x^5) / ((1 - 2*x)*(1 - 57*x + 489*x^2 - 1233*x^3 + 360*x^4)). - Colin Barker, Jul 07 2018
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EXAMPLE
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Some solutions for n=4:
..0..1..1....0..1..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0
..0..1..0....0..2..2....0..1..1....0..1..1....0..1..1....0..1..1....1..1..1
..0..1..2....1..2..1....0..1..2....2..1..2....1..2..0....2..1..2....0..2..0
..3..2..1....1..3..2....2..0..2....0..2..1....1..0..1....2..1..2....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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