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A199892 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 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A199898

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

EXAMPLE

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

CROSSREFS

Sequence in context: A077841 A126945 A191641 * A152809 A034539 A029609

Adjacent sequences:  A199889 A199890 A199891 * A199893 A199894 A199895

KEYWORD

nonn

AUTHOR

R. H. Hardin Nov 11 2011

STATUS

approved

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Last modified February 21 02:02 EST 2020. Contains 332086 sequences. (Running on oeis4.)