A056304 Number of primitive (period n) n-bead necklace structures using exactly three different colored beads.

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

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. [See A056391 for pdf file of Chap. 2]

Links

Table of n, a(n) for n=1..27.

Formula

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

Crossrefs

Column 3 of A107424.

Cf. A056288.

Sequence in context: A300692 A076076 A136194 * A063106 A096295 A215580

Adjacent sequences: A056301 A056302 A056303 * A056305 A056306 A056307

Keyword

nonn

Author

Marks R. Nester

Status

approved