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A251214
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Number of (n+1) X (3+1) 0..1 arrays with no 2 X 2 subblock having zero or two 1s.
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1
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49, 191, 758, 3089, 12503, 50912, 206715, 840931, 3417338, 13896689, 56488843, 229680232, 933724343, 3796257055, 15433585490, 62747204885, 255100769239, 1037135769960, 4216531992291, 17142642411675, 69694499491242
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 2*a(n-1) + 17*a(n-2) - 20*a(n-3) - 85*a(n-4) + 68*a(n-5) + 146*a(n-6) - 84*a(n-7) - 56*a(n-8) + 24*a(n-9).
Empirical g.f.: x*(49 + 93*x - 457*x^2 - 694*x^3 + 1424*x^4 + 1456*x^5 - 1592*x^6 - 692*x^7 + 384*x^8) / (1 - 2*x - 17*x^2 + 20*x^3 + 85*x^4 - 68*x^5 - 146*x^6 + 84*x^7 + 56*x^8 - 24*x^9). - Colin Barker, Nov 27 2018
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EXAMPLE
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Some solutions for n=4:
..1..1..1..1....1..1..1..1....1..0..1..1....0..1..0..1....0..0..1..0
..1..0..1..0....0..1..1..0....1..1..1..1....0..0..0..0....1..0..0..0
..1..1..1..1....1..1..0..0....1..1..0..1....1..0..1..0....1..1..0..1
..1..0..1..0....0..1..1..0....0..1..1..1....1..1..1..1....1..1..1..1
..1..1..1..1....1..1..1..1....1..1..1..1....0..1..1..1....1..0..1..1
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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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