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A209377
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1/4 the number of (n+1) X 4 0..2 arrays with every 2 X 2 subblock having distinct edge sums.
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1
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16, 34, 64, 156, 320, 840, 1792, 4848, 10496, 28704, 62464, 171456, 373760, 1027200, 2240512, 6160128, 13438976, 36954624, 80625664, 221715456, 483737600, 1330268160, 2902392832, 7981559808, 17414291456, 47889260544, 104485617664
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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) = 8*a(n-2) - 12*a(n-4).
Empirical g.f.: 2*x*(8 + 17*x - 32*x^2 - 58*x^3) / ((1 - 2*x^2)*(1 - 6*x^2)). - Colin Barker, Jul 09 2018
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EXAMPLE
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Some solutions for n=4:
..0..2..0..0....1..2..2..2....1..2..1..2....2..2..1..2....0..2..2..1
..1..2..1..2....0..0..1..0....0..0..0..2....1..0..0..0....0..1..0..0
..0..2..0..2....1..2..2..2....1..2..1..2....2..2..1..2....2..2..2..1
..0..1..0..1....0..0..1..0....0..2..0..0....1..0..0..0....0..1..0..0
..2..2..2..2....1..2..2..2....1..2..1..2....2..2..1..2....2..2..2..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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