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A223442
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4-level binary fanout graph coloring a rectangular array: number of n X 1 0..14 arrays where 0..14 label nodes of a graph with edges 0,1 1,3 3,5 3,6 1,4 4,7 4,8 0,2 2,9 9,11 9,12 2,10 10,13 10,14 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph.
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1
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15, 28, 66, 144, 336, 752, 1752, 3936, 9168, 20608, 48000, 107904, 251328, 564992, 1315968, 2958336, 6890496, 15490048, 36079104, 81106944, 188912640, 424681472, 989159424, 2223661056, 5179305984, 11643240448, 27119198208, 60964798464
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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) = 6*a(n-2) - 4*a(n-4).
Empirical g.f.: x*(3 + 2*x)*(5 + 6*x - 12*x^2) / (1 - 6*x^2 + 4*x^4). - Colin Barker, Aug 20 2018
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EXAMPLE
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Some solutions for n=3:
.12...13....3....7....1....8....2....2....9....2....6....1....0....2...11....0
..9...10....1....4....0....4....0....9....2....0....3....0....2....9....9....2
..2...13....0....8....2....8....1...12...10....2....1....1....9...11....2....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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