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A230588
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Number of nX2 0..5 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 6, and upper left element zero
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2
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0, 0, 2, 8, 30, 120, 506, 2144, 9030, 37920, 159218, 668792, 2809710, 11804040, 49589354, 208325456, 875178390, 3676643760, 15445668962, 64887621608, 272594409150, 1145175432600, 4810908576986, 20210738740544, 84905783253990
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OFFSET
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1,3
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 5*a(n-1) -5*a(n-2) +5*a(n-3) +8*a(n-4).
Empirical: G.f. 2*x^3*(-1+x) / ( -1+5*x-5*x^2+5*x^3+8*x^4 ). - R. J. Mathar, Oct 27 2013
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EXAMPLE
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All solutions for n=4
..0..5....0..1....0..5....0..1....0..5....0..1....0..5....0..1
..1..4....1..2....1..4....5..2....1..0....5..2....1..2....3..2
..2..3....0..3....2..3....4..3....2..5....4..3....0..3....4..1
..1..0....5..4....1..2....1..2....3..4....3..2....5..4....5..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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