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A199892
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Number of -2..2 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative
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1
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1, 5, 15, 49, 159, 533, 1783, 6027, 20437, 69665, 238191, 817083, 2809845, 9685397, 33450675, 115736335, 401065951, 1391807783, 4836111471, 16823523661, 58586196339, 204217367081, 712482836479, 2487770630935, 8693076444331
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OFFSET
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1,2
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COMMENTS
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LINKS
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EXAMPLE
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Some solutions for n=6
.-2....1...-1...-1...-1....1....1...-2...-1....0....2....0....1....0...-2....0
..0...-1....0....0....2...-1...-1....0....0....1....0...-2....0....2....1....1
..0....0....0...-1...-1....0....1....2....0...-1....0....0...-2...-2...-1...-1
..0....2....0....2....2....0...-2...-1....2....0...-2....2....0....1....2....1
..2...-2....2...-1....0....0....0....1...-2....1....0...-2....1...-1...-1....0
..0....0...-1....1...-2....0....1....0....1...-1....0....2....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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