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A200051 Number of -2..2 arrays x(0..n-1) of n elements with zero sum and elements alternately strictly increasing and strictly decreasing 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A200057

LINKS

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

EXAMPLE

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

CROSSREFS

Sequence in context: A218208 A207095 A126358 * A200663 A200464 A099234

Adjacent sequences:  A200048 A200049 A200050 * A200052 A200053 A200054

KEYWORD

nonn

AUTHOR

R. H. Hardin Nov 13 2011

STATUS

approved

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Last modified October 27 01:02 EDT 2020. Contains 338035 sequences. (Running on oeis4.)