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A208962 Number of n-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero and first and second differences in -n..n. 0
1, 1, 2, 8, 40, 495, 7425, 140429, 3014206, 73238115, 2000005946 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Diagonal of A208970.

LINKS

Table of n, a(n) for n=1..11.

EXAMPLE

Some solutions for n=5:

.-2...-3...-3...-1...-2...-1...-1...-2...-2...-1...-2....0...-2...-2...-3...-3

.-2...-3...-1....0...-1....0...-1...-1....0....0...-1....0....0....0...-2...-3

..1....2....1...-1....2....0....1....2....2...-1....1....0....0....1....3....1

..1....2....3....0....0....0....0....1...-1....1....2....0....1....0....3....3

..2....2....0....2....1....1....1....0....1....1....0....0....1....1...-1....2

CROSSREFS

Sequence in context: A111394 A140363 A280921 * A012597 A012534 A092354

Adjacent sequences:  A208959 A208960 A208961 * A208963 A208964 A208965

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 03 2012

STATUS

approved

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Last modified September 20 14:21 EDT 2020. Contains 337264 sequences. (Running on oeis4.)