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A208715 Number of n-bead necklaces labeled with numbers 1..n allowing reversal, with no adjacent beads differing by more than 1. 1
1, 3, 7, 18, 38, 100, 224, 600, 1498, 4124, 11054, 31347, 87887, 253251, 727867, 2117551, 6159994, 18022052, 52757222, 154874172, 454989753, 1338737083, 3941860229, 11618101775, 34264747423, 101127761931, 298632667837, 882370316215, 2608423280534, 7714578529582 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
EXAMPLE
All solutions for n=3:
..2....2....1....3....2....1....1
..2....2....1....3....3....2....1
..2....3....2....3....3....2....1
CROSSREFS
Diagonal of A208721.
Sequence in context: A006124 A197182 A074587 * A302408 A076700 A265007
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 01 2012
EXTENSIONS
a(17)-a(30) from Andrew Howroyd, Mar 03 2017
STATUS
approved

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Last modified May 19 09:42 EDT 2024. Contains 372683 sequences. (Running on oeis4.)