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A208963 Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero and first and second differences in -1..1. 1
1, 1, 1, 1, 1, 2, 2, 4, 4, 7, 7, 14, 16, 32, 46, 90, 140, 258, 416, 746, 1245, 2228, 3845, 6929, 12194, 21990, 39113, 70544, 126293, 228168, 410887, 744377, 1346837, 2446229, 4441502, 8084433, 14717678, 26841848, 48977823, 89494630, 163634188, 299532409 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..100

EXAMPLE

All solutions for n=8:

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

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

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

..0....0....0....0

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

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

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

..0....0....0....0

CROSSREFS

Column 1 of A208970.

Sequence in context: A131524 A089075 A325098 * A011142 A232047 A060029

Adjacent sequences:  A208960 A208961 A208962 * A208964 A208965 A208966

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 03 2012

EXTENSIONS

a(34)-a(42) from Andrew Howroyd, Mar 12 2017

STATUS

approved

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Last modified December 5 21:00 EST 2019. Contains 329779 sequences. (Running on oeis4.)