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A275144
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Number of 4 X n 0..2 arrays with no element equal to any value at offset (-2,-2) (-1,-2) or (0,-1) and new values introduced in order 0..2.
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1
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14, 216, 400, 1088, 2320, 6464, 17872, 49792, 139664, 392448, 1102416, 3095808, 8693584, 24414784, 68567696, 192568832, 540817040, 1518847552, 4265581328, 11979603776, 33643929040, 94486756224, 265359817104, 745245528576
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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) = 5*a(n-1) - 9*a(n-2) + 10*a(n-3) - 6*a(n-4) + a(n-5) for n>9.
Empirical g.f.: 2*x*(7 + 73*x - 277*x^2 + 446*x^3 - 798*x^4 + 969*x^5 - 1132*x^6 + 768*x^7 - 128*x^8) / ((1 - x)*(1 - 4*x + 5*x^2 - 5*x^3 + x^4)). - Colin Barker, Feb 01 2019
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EXAMPLE
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Some solutions for n=5:
..0..1..0..1..2. .0..1..0..2..1. .0..1..0..1..2. .0..1..0..2..1
..0..2..1..0..1. .1..2..1..0..1. .1..2..1..0..1. .0..2..1..2..1
..1..0..1..0..2. .1..0..2..0..2. .2..0..2..0..2. .0..2..1..0..2
..2..0..2..1..2. .1..2..0..1..0. .0..1..0..1..0. .2..0..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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