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A208602 Number of n-bead necklaces labelled with numbers -1..1 not allowing reversal, with sum zero 1
1, 2, 3, 6, 11, 26, 57, 142, 351, 902, 2333, 6166, 16381, 44046, 119183, 324862, 890291, 2453126, 6789309, 18869426, 52635789, 147325510, 413618615, 1164517198, 3287073461, 9300516890, 26372968983, 74937177538, 213333642443, 608400919106 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 1 of A208597

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..31

EXAMPLE

All solutions for n=5

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

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

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

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

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

CROSSREFS

Sequence in context: A107113 A156807 A032256 * A051603 A094927 A024423

Adjacent sequences:  A208599 A208600 A208601 * A208603 A208604 A208605

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 29 2012

STATUS

approved

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Last modified September 2 15:16 EDT 2014. Contains 246361 sequences.