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A268013
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Number of n X 1 0..2 arrays with every repeated value in every row and column greater than or equal to the previous repeated value.
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3
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3, 9, 27, 78, 222, 622, 1722, 4719, 12821, 34575, 92637, 246788, 654120, 1725900, 4535172, 11872941, 30977943, 80575109, 208983471, 540606474, 1395061474, 3591893274, 9228660318, 23664610747, 60570324105, 154763821419, 394795932561
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OFFSET
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1,1
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COMMENTS
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Column 1 of A268019.
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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) - 9*a(n-2) - 4*a(n-3) + 9*a(n-4) + 6*a(n-5) + a(n-6).
Empirical g.f.: x*(3 - 9*x + 9*x^3 + 6*x^4 + x^5) / (1 - 2*x - x^2)^3. - Colin Barker, Feb 26 2018
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EXAMPLE
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Some solutions for n=8:
..1....2....2....1....2....1....0....0....2....1....2....0....2....2....2....2
..0....1....2....2....0....1....0....0....0....0....0....2....1....0....0....0
..2....1....2....0....0....2....1....1....2....1....2....0....2....2....0....2
..0....1....2....2....0....2....0....2....0....1....0....0....0....0....1....2
..0....0....0....2....2....1....0....2....2....2....2....1....0....1....0....0
..1....2....1....1....1....0....2....0....2....2....1....1....0....2....1....2
..1....1....2....2....2....2....2....2....0....0....0....2....0....2....2....2
..2....1....1....0....0....1....0....1....1....2....0....0....0....1....0....1
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CROSSREFS
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Cf. A268019.
Sequence in context: A139561 A152169 A241574 * A269613 A006810 A090401
Adjacent sequences: A268010 A268011 A268012 * A268014 A268015 A268016
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Jan 24 2016
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STATUS
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approved
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