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A231241
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Number of n X 3 0..3 arrays x(i,j) with each element horizontally, diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero.
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1
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0, 14, 78, 552, 3820, 26658, 185074, 1287036, 8947088, 62202118, 432432502, 3006318960, 20900215412, 145300370954, 1010142438650, 7022609687108, 48821873295640, 339414466598958, 2359642763446654, 16404468638111480
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 4*a(n-1) +16*a(n-2) +26*a(n-3) +37*a(n-4) +6*a(n-5).
Empirical g.f.: 2*x^2*(7 + 11*x + 8*x^2) / (1 - 4*x - 16*x^2 - 26*x^3 - 37*x^4 - 6*x^5). - Colin Barker, Feb 09 2018
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EXAMPLE
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Some solutions for n=4:
..0..1..0....0..3..2....0..3..0....0..1..0....0..3..2....0..1..2....0..1..0
..2..3..2....2..1..0....2..1..0....0..3..2....0..1..0....2..3..0....0..3..2
..0..3..0....2..3..2....2..3..2....0..3..2....0..3..0....0..3..2....2..1..0
..2..1..2....2..1..0....2..1..2....2..1..2....0..1..2....0..1..2....2..3..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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