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A208938 Number of n-bead necklaces labeled with numbers -1..1 not allowing reversal, with sum zero with no three beads in a row equal. 1
1, 2, 2, 5, 8, 20, 38, 88, 196, 464, 1088, 2628, 6344, 15554, 38318, 95170, 237536, 596286, 1503098, 3805452, 9668776, 24650428, 63035390, 161648194, 415589336, 1071003162, 2766083600, 7158525512, 18561001524, 48210881198, 125430649666 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 1 of A208945.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..33

EXAMPLE

All solutions for n=5:

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

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

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

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

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

CROSSREFS

Sequence in context: A257517 A095005 A209066 * A019086 A076949 A040009

Adjacent sequences:  A208935 A208936 A208937 * A208939 A208940 A208941

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 03 2012

STATUS

approved

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Last modified December 12 20:12 EST 2019. Contains 329961 sequences. (Running on oeis4.)