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A228799
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Number of 4 X n binary arrays with top left element equal to 1 and no two ones adjacent horizontally or nw-se.
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1
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8, 13, 156, 586, 3957, 19474, 111966, 596273, 3292024, 17872116, 97776195, 533053286, 2910670434, 15882108643, 86688323910, 473098799920, 2582083666591, 14092131350712, 76910993201528, 419756836650551, 2290910858988482
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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) = a(n-1) + 20*a(n-2) + 27*a(n-3) - 14*a(n-4) - 25*a(n-5) + 4*a(n-6) + 5*a(n-7) - a(n-8).
Empirical g.f.: x*(8 + 5*x - 17*x^2 - 46*x^3 + 12*x^4 - 33*x^5 + 7*x^6) / ((1 + x)*(1 + 2*x - x^2)*(1 - 4*x - 9*x^2 + 5*x^3 + 4*x^4 - x^5)). - Colin Barker, Sep 13 2018
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EXAMPLE
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Some solutions for n=4:
..1..0..0..1....1..0..0..1....1..0..1..0....1..0..0..0....1..0..0..1
..0..0..1..0....1..0..0..1....1..0..1..0....1..0..0..1....0..0..0..0
..0..1..0..0....1..0..1..0....1..0..0..0....1..0..1..0....0..0..0..0
..0..0..0..0....0..0..0..0....0..0..0..1....0..0..1..0....0..1..0..0
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CROSSREFS
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Row 4 of A228796.
Sequence in context: A107764 A306131 A177183 * A329499 A220393 A344659
Adjacent sequences: A228796 A228797 A228798 * A228800 A228801 A228802
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Sep 04 2013
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STATUS
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approved
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