A056305 - OEIS

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A056305

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

0, 0, 0, 1, 2, 13, 50, 220, 866, 3435, 13250, 51061, 194810, 742601, 2823764, 10738660, 40843370, 155493872, 592614050, 2261622287, 8643289484, 33080907357, 126797503250, 486710920300, 1870851589552

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,5

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..25.

FORMULA

Sum mu(d)*A056297(n/d) where d|n. Alternatively, A056300(n)-A002075(n)..

CROSSREFS

Column 4 of A107424.

Cf. A056289.

Sequence in context: A072416 A319759 A254784 * A056297 A241892 A037383

Adjacent sequences: A056302 A056303 A056304 * A056306 A056307 A056308

KEYWORD

nonn

AUTHOR

Marks R. Nester

STATUS

approved