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A209024
Number of n-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero and first differences in -n..n.
0
1, 2, 4, 23, 187, 2798, 52208, 1210780, 32915700, 1029158718, 36366029268, 1434017630862, 62448855324545, 2977529703278272, 154305670613042906, 8637641797383212010, 519466811614545786362, 33406493488132547194879, 2287819864082225737308655, 166242770253180661727941435
OFFSET
1,2
EXAMPLE
Some solutions for n=6:
.-4...-6...-4...-3...-3...-2...-5...-4...-5...-3...-3...-5...-4...-6...-3...-4
..0...-2...-2...-1...-2....0...-1....0...-3...-1...-2...-5...-3....0...-2....0
.-2....3....3....1....3....1....2...-1....2...-1....4....0....0....0...-1....2
..4....3....4....3...-1...-2....3....5....0....1...-1....6....3....0....0....3
..0....4...-1....0....1....1....2....0....5....4....2....3....4....6....4...-2
..2...-2....0....0....2....2...-1....0....1....0....0....1....0....0....2....1
CROSSREFS
Diagonal of A209032.
Sequence in context: A366224 A009313 A009317 * A081680 A269573 A147761
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 04 2012
EXTENSIONS
a(12)-a(20) from Andrew Howroyd, Mar 19 2017
STATUS
approved