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A056304 Number of primitive (period n) n-bead necklace structures using exactly three different colored beads. 3
0, 0, 1, 2, 5, 17, 43, 124, 338, 941, 2591, 7234, 20125, 56407, 158349, 446492, 1262225, 3580330, 10181479, 29031306, 82968799, 237642659, 682014587, 1960974220, 5647919640, 16292741605, 47069104274 (list; graph; refs; listen; history; internal format)
OFFSET

1,4

COMMENTS

Turning over the necklace is not allowed. Colors may be permuted without changing the necklace structure.

REFERENCES

M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia.

FORMULA

sum mu(d)*A056296(n/d) where d|n. Alternatively, A002075(n)-A000048(n)..

CROSSREFS

Cf. A056288.

Sequence in context: A007351 A076076 A136194 * A063106 A096295 A074494

Adjacent sequences:  A056301 A056302 A056303 * A056305 A056306 A056307

KEYWORD

nonn

AUTHOR

Marks R. Nester (nesterm(AT)dpi.qld.gov.au)

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Last modified February 16 09:00 EST 2012. Contains 205904 sequences.