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A222993
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Number of n X 2 0..2 arrays with successive rows and columns fitting to straight lines with nondecreasing slope, with a single point array taken as having zero slope
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5
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9, 50, 222, 867, 3123, 10660, 35064, 112373, 353517, 1097430, 3374226, 10302919, 31301991, 94757960, 286108908, 862258905, 2595165345, 7803321850, 23447714310, 70422834731, 211436276379, 634661150700, 1904721649632, 5715708452797
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OFFSET
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1,1
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COMMENTS
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Column 2 of A222996.
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..33
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FORMULA
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Empirical: a(n) = 9*a(n-1) - 31*a(n-2) + 51*a(n-3) - 40*a(n-4) + 12*a(n-5).
Conjectures from Colin Barker, Feb 19 2018: (Start)
G.f.: x*(9 - 31*x + 51*x^2 - 40*x^3 + 12*x^4) / ((1 - x)^2*(1 - 2*x)^2*(1 - 3*x)).
a(n) = (-13 - 2^(6+n) + 3^(4+n) - 2*(1+2^(4+n))*n) / 4.
(End)
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EXAMPLE
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Some solutions for n=3:
..2..0....1..1....2..0....1..0....0..1....1..0....2..2....0..0....1..1....1..0
..0..0....1..1....1..1....2..2....0..1....2..2....1..1....1..2....0..0....2..2
..0..1....1..2....2..2....0..1....1..2....0..2....0..1....0..2....1..1....1..1
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CROSSREFS
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Sequence in context: A084367 A006974 A279979 * A171480 A257589 A231413
Adjacent sequences: A222990 A222991 A222992 * A222994 A222995 A222996
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Mar 11 2013
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STATUS
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approved
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