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A184766
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Number of (n+1) X 3 0..3 arrays with every 2 X 2 subblock singular.
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1
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424, 8272, 108496, 1792144, 27993232, 454774672, 7339536784, 119205236368, 1934859805840, 31437977902480, 510797840746384, 8300795694017680, 134894624057920144, 2192213833325394832, 35626484733088902544
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 20*a(n-1) - 19*a(n-2) - 792*a(n-3) + 1800*a(n-4).
Empirical g.f.: 8*x*(53 - 26*x - 6111*x^2 + 14400*x^3) / (1 - 20*x + 19*x^2 + 792*x^3 - 1800*x^4). - Colin Barker, Apr 15 2018
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EXAMPLE
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Some solutions for 5 X 3:
..0..0..0....2..0..0....0..0..0....0..0..0....2..0..0....2..0..0....2..0..0
..2..0..1....0..0..0....0..0..3....2..3..1....0..0..3....0..0..2....2..0..2
..1..0..2....0..0..1....0..0..0....0..0..0....2..0..0....0..0..0....3..0..3
..1..0..1....2..0..3....2..2..2....2..0..1....2..0..2....0..0..0....0..0..2
..1..0..0....0..0..1....2..2..2....2..0..0....3..0..0....3..2..1....1..0..2
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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