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A183325
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Number of nX4 binary arrays with each 1 adjacent to exactly two other 1s
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1
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1, 4, 10, 27, 72, 179, 447, 1139, 2912, 7434, 18949, 48256, 122905, 313153, 797993, 2033404, 5181138, 13201355, 33636776, 85706587, 218381247, 556436971, 1417803304, 3612566114, 9204828661, 23453934912, 59760710321, 152270499073
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OFFSET
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1,2
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COMMENTS
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Column 4 of A183328
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..200
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FORMULA
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Empirical: a(n)=3*a(n-1)-2*a(n-2)+2*a(n-3)+2*a(n-5)-5*a(n-7)-3*a(n-8)
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EXAMPLE
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Some solutions for 8X4
..1..1..1..1....1..1..1..1....0..0..0..0....1..1..1..0....0..1..1..0
..1..0..0..1....1..0..0..1....0..0..0..0....1..0..1..1....0..1..1..0
..1..1..0..1....1..0..1..1....0..0..1..1....1..0..0..1....0..0..0..0
..0..1..0..1....1..0..1..0....0..0..1..1....1..0..0..1....0..1..1..1
..0..1..0..1....1..0..1..1....0..0..0..0....1..0..0..1....0..1..0..1
..0..1..1..1....1..0..0..1....0..0..1..1....1..0..0..1....1..1..0..1
..0..0..0..0....1..0..0..1....0..0..1..1....1..1..1..1....1..0..0..1
..0..0..0..0....1..1..1..1....0..0..0..0....0..0..0..0....1..1..1..1
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CROSSREFS
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Sequence in context: A122744 A192879 A077923 * A052982 A108672 A000495
Adjacent sequences: A183322 A183323 A183324 * A183326 A183327 A183328
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin Jan 03 2011
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STATUS
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approved
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