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A200051
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Number of -2..2 arrays x(0..n-1) of n elements with zero sum and elements alternately strictly increasing and strictly decreasing
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1
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1, 4, 10, 26, 68, 178, 472, 1276, 3462, 9496, 26024, 71956, 198740, 552814, 1535556, 4290252, 11968194, 33553214, 93917400, 264020106, 741024426, 2087799972, 5872999754, 16577458520, 46720454112, 132081262316, 372843051320
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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
.-1...-1....0....2....0....0....0....0....0...-2....0....0....1...-1...-2...-2
..1...-2...-1....1....1...-1....1....1...-1....1....2...-2....2....1....1....1
..0....2....0....2...-2....2...-2...-1....1...-1...-2....0...-2....0....0...-1
..2...-2...-1...-2....0...-2....1....0....0....1....0...-1....2....1....1....1
.-2....2....2...-1...-1....1...-2...-2....1....0...-1....2...-2...-1...-2...-1
..0....1....0...-2....2....0....2....2...-1....1....1....1...-1....0....2....2
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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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