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A208534
Number of n-bead necklaces of 7 colors not allowing reversal, with no adjacent beads having the same color.
0
7, 21, 70, 336, 1554, 7826, 39990, 210126, 1119790, 6047412, 32981550, 181402676, 1004668770, 5597460306, 31345666730, 176319474366, 995685849690, 5642220380006, 32071565263710, 182807925027504
OFFSET
1,1
EXAMPLE
Some solutions for n=4
..1....1....2....3....3....1....1....2....1....3....1....3....4....1....1....1
..3....5....3....5....5....6....3....7....5....7....4....7....7....2....3....5
..1....7....4....6....3....1....4....4....7....6....3....5....5....4....6....4
..5....2....3....7....7....6....5....3....6....4....2....4....6....7....2....2
CROSSREFS
Column 7 of A208535.
Sequence in context: A245404 A215494 A146533 * A135576 A153497 A146247
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 27 2012
STATUS
approved