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A066313 Number of aperiodic necklaces with n red or blue beads such that two necklaces are equivalent under the operation (turn necklace over and switch the two colors). 2
1, 1, 1, 2, 3, 6, 9, 18, 28, 57, 93, 181, 315, 612, 1091, 2100, 3855, 7392, 13797, 26436, 49929, 95790, 182361, 350440, 671088, 1292445, 2485504, 4797261, 9256395, 17903316, 34636833, 67124160, 130150493, 252675975, 490853403 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Also number of aperiodic cyclic graphs with oriented edges on n nodes that can be turned over.

LINKS

Table of n, a(n) for n=1..35.

N. J. A. Sloane, Transforms

Index entries for sequences related to bracelets

FORMULA

Moebius transform of A053656.

EXAMPLE

The equivalence requires the "turning over" operation and the "switching colors" operation to be simultaneous; thus rrrbbrrb is equivalent to rbbrrbbb, but not to bbbrrbbr.

CROSSREFS

Sequence in context: A182522 A165647 A191398 * A224958 A018499 A107847

Adjacent sequences:  A066310 A066311 A066312 * A066314 A066315 A066316

KEYWORD

nonn

AUTHOR

Christian G. Bower, Dec 13 2001; revised Apr 25 2006

STATUS

approved

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Last modified December 19 12:22 EST 2014. Contains 252224 sequences.