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A209337 Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero with no three beads in a row equal. 0
1, 2, 1, 4, 5, 14, 21, 51, 102, 249, 555, 1358, 3201, 7890, 19232, 47869, 118955, 298875, 752039, 1904621, 4835666, 12330144, 31521037, 80836979, 207803455, 535535393, 1383064966, 3579351724, 9280561947 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 1 of A209344.

LINKS

Table of n, a(n) for n=1..29.

EXAMPLE

Some solutions for n=10:

.-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1

..0....0...-1....0...-1....0....0....0....0...-1....0....0....0....0....0....0

.-1....0....0....0....0....0....0...-1...-1....0...-1....0....0...-1....1...-1

..0...-1....0....1...-1...-1...-1....0....0...-1....1...-1....1....1....0....0

..0....0...-1....0....1....0....1....1....1....1....1....0...-1...-1...-1....0

..1....1....0...-1....0....0...-1...-1...-1....1...-1....1....1....1....1....1

..1....0....1....1....1....1....1....1....1...-1....0...-1....0....0...-1....0

..0....1....0...-1....0....0....0....0...-1....1...-1....0....0....1....1....1

.-1...-1....1....1....1....0....0....0....1....0....1....1...-1...-1...-1....0

..1....1....1....0....0....1....1....1....1....1....1....1....1....1....1....0

CROSSREFS

Sequence in context: A350087 A091232 A336398 * A243004 A137424 A083007

Adjacent sequences:  A209334 A209335 A209336 * A209338 A209339 A209340

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 06 2012

STATUS

approved

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Last modified August 13 20:49 EDT 2022. Contains 356107 sequences. (Running on oeis4.)