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A235549
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Number of (n+1) X (1+1) 0..1 arrays with the sum of each 2 X 2 subblock two extreme terms minus its two median terms lexicographically nondecreasing rowwise and columnwise.
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2
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16, 46, 120, 288, 660, 1456, 3136, 6624, 13808, 28480, 58304, 118656, 240448, 485632, 978432, 1967616, 3951360, 7926784, 15889408, 31832064, 63742976, 127602688, 255377408, 511008768, 1022390272, 2045329408, 4091461632, 8184102912
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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) = 2*a(n-1) + 4*a(n-2) - 8*a(n-3) - 4*a(n-4) + 8*a(n-5).
Empirical g.f.: 2*x*(8 + 7*x - 18*x^2 - 4*x^3 + 18*x^4) / ((1 - 2*x)*(1 - 2*x^2)^2). - Colin Barker, Mar 19 2018
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EXAMPLE
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Some solutions for n=5:
..0..1....0..0....1..0....1..1....1..0....1..1....0..0....1..1....0..1....0..0
..1..1....1..1....1..0....1..0....1..0....1..0....1..1....1..0....1..0....0..0
..0..1....0..0....0..1....1..0....0..1....1..1....0..0....1..1....1..0....0..0
..1..1....0..0....0..1....1..0....0..1....1..0....0..0....0..1....0..0....0..0
..0..0....0..0....0..0....1..0....0..1....1..1....1..1....0..1....1..0....0..0
..0..0....1..1....1..0....0..0....1..0....0..0....1..1....0..1....0..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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