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A209481 Number of n-bead necklaces labeled with numbers -4..4 allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2. 0
1, 5, 12, 72, 390, 2606, 17771, 128598, 950292, 7180767, 55056590, 427567892, 3354737555, 26555548849 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 4 of A209485.

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

Some solutions for n=7:

.-3...-4...-3...-4...-3...-4...-4...-3...-2...-4...-4...-3...-2...-4...-3...-1

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

..4....3....4....0....0....4....1....4...-2...-4....1...-2....1....1...-2...-1

..0....1....2....4....3...-3...-1...-2....0....3...-2....0...-2...-3....2....0

.-1...-1...-2....2....2....1....1...-1....2...-4....2....3...-1...-2....0....0

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

.-1....4....1....2....1....1....1....4....3....4....3....3....4....3....2....4

CROSSREFS

Sequence in context: A297644 A242043 A156236 * A209340 A128323 A202203

Adjacent sequences:  A209478 A209479 A209480 * A209482 A209483 A209484

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 09 2012

STATUS

approved

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Last modified August 12 05:33 EDT 2020. Contains 336438 sequences. (Running on oeis4.)