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A232510
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Number of (n+1)X(3+1) 0..2 arrays with every element next to itself plus and minus one within the range 0..2 horizontally, diagonally or antidiagonally, with no adjacent elements equal
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1
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16, 32, 128, 400, 1344, 4416, 14608, 48224, 159296, 526096, 1737600, 5738880, 18954256, 62601632, 206759168, 682879120, 2255396544, 7449068736, 24602602768, 81256877024, 268373233856, 886376578576, 2927502969600, 9668885487360
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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) = 2*a(n-1) +4*a(n-2) +a(n-3).
Empirical: G.f.: -16*x / ( (1+x)*(x^2+3*x-1) ), which means a(n) is 16 times 1, 2, 8, 25, 84, 276 and so on with pairs of adjacent numbers summing to A006190. - R. J. Mathar, Nov 23 2014
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EXAMPLE
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Some solutions for n=7
..0..1..2..1....0..1..0..1....0..1..0..1....0..1..0..1....2..1..0..1
..0..1..0..1....2..1..2..1....2..1..2..1....2..1..2..1....0..1..2..1
..2..1..2..1....2..1..2..1....2..1..2..1....0..1..0..1....2..1..0..1
..2..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1....2..1..2..1
..2..1..2..1....2..1..2..1....2..1..0..1....2..1..2..1....0..1..2..1
..0..1..0..1....0..1..0..1....0..1..2..1....0..1..2..1....0..1..0..1
..2..1..2..1....2..1..0..1....0..1..2..1....0..1..0..1....0..1..2..1
..0..1..0..1....2..1..2..1....2..1..0..1....0..1..2..1....0..1..0..1
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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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