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A184541
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Number of (n+2) X 4 binary arrays with each 3 X 3 subblock having rows and columns in lexicographically nondecreasing order.
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1
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89, 193, 340, 537, 792, 1114, 1513, 2000, 2587, 3287, 4114, 5083, 6210, 7512, 9007, 10714, 12653, 14845, 17312, 20077, 23164, 26598, 30405, 34612, 39247, 44339, 49918, 56015, 62662, 69892, 77739, 86238, 95425, 105337, 116012, 127489, 139808, 153010
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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) = (1/24)*n^4 + (3/4)*n^3 + (383/24)*n^2 + (201/4)*n + 22.
G.f.: x*(89 - 252*x + 265*x^2 - 123*x^3 + 22*x^4) / (1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.
(End)
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EXAMPLE
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Some solutions for 6 X 4:
..0..0..0..0....0..0..0..1....0..0..0..0....0..0..0..1....0..0..0..1
..0..0..0..1....0..0..0..1....0..0..0..1....0..0..0..1....0..0..1..1
..0..0..0..1....0..0..0..1....0..0..0..1....0..0..0..1....0..1..1..1
..0..0..0..1....0..0..0..1....0..0..1..1....0..0..0..1....0..1..1..1
..0..0..1..0....0..0..1..0....0..1..0..0....0..0..0..1....1..1..1..1
..0..1..1..0....0..0..1..1....1..1..0..0....0..0..0..1....1..1..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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