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A228980
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Number of n X 2 0..1 arrays of the median of the corresponding element, the element to the east and the element to the south in a larger (n+1) X 3 0..1 array.
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1
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4, 16, 64, 252, 992, 3900, 15328, 60228, 236624, 929580, 3651712, 14344836, 56349296, 221349132, 869490976, 3415475172, 13416415184, 52701313836, 207017071552, 813187592388, 3194296661552, 12547572276300, 49288333901920
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OFFSET
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1,1
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..210
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FORMULA
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Empirical: a(n) = 6*a(n-1) - 7*a(n-2) - 6*a(n-3) + 6*a(n-4).
Empirical g.f.: 4*x*(1 - 2*x - x^2 + x^3) / (1 - 6*x + 7*x^2 + 6*x^3 - 6*x^4). - Colin Barker, Sep 13 2018
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EXAMPLE
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Some solutions for n=4:
..0..1....1..0....0..1....0..1....1..0....1..0....1..1....1..1....0..1....1..0
..1..0....1..1....0..1....0..0....1..1....1..0....0..1....0..0....0..0....1..1
..0..0....0..1....0..0....1..1....1..1....1..0....1..0....1..1....0..0....0..0
..1..0....0..1....0..1....1..1....1..0....1..0....1..1....1..0....0..1....1..0
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CROSSREFS
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Column 2 of A228986.
Sequence in context: A259898 A307945 A269771 * A188714 A005755 A269651
Adjacent sequences: A228977 A228978 A228979 * A228981 A228982 A228983
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Sep 10 2013
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STATUS
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approved
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