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A234825
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Number of (n+1) X (1+1) 0..2 arrays with each 2 X 2 subblock having the number of clockwise edge increases less than or equal to the number of counterclockwise edge increases.
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1
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69, 516, 3843, 28602, 212850, 1583955, 11787201, 87715899, 652748544, 4857507711, 36147734568, 268997764212, 2001779586225, 14896486309185, 110854015040601, 824933638413864, 6138844024165119, 45682954601641506, 339955264040033718
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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) = 9*a(n-1) - 12*a(n-2) + 3*a(n-3).
Empirical g.f.: 3*x*(23 - 35*x + 9*x^2) / (1 - 9*x + 12*x^2 - 3*x^3). - Colin Barker, Oct 16 2018
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EXAMPLE
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Some solutions for n=4:
..2..0....2..2....2..1....1..1....0..2....0..1....2..2....1..2....2..2....1..0
..2..0....1..2....2..2....0..0....2..1....0..0....1..1....2..0....0..1....1..2
..0..0....1..1....0..0....1..0....2..0....0..0....2..1....1..2....1..0....1..2
..1..2....2..1....1..1....1..1....0..2....1..1....0..2....2..2....1..2....2..1
..2..1....2..0....2..1....1..2....0..0....2..1....0..2....1..1....1..1....1..0
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CROSSREFS
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Column 1 of A234832.
Sequence in context: A253342 A253335 A234832 * A251010 A251003 A211692
Adjacent sequences: A234822 A234823 A234824 * A234826 A234827 A234828
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Dec 31 2013
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STATUS
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approved
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