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A056354 Number of bracelet structures using a maximum of four different colored beads. 8
1, 1, 2, 3, 7, 11, 33, 73, 237, 703, 2433, 8309, 30108, 108991, 403262, 1497070, 5607437, 21076571, 79595990, 301492045, 1145560579, 4363503684, 16660204452, 63741248201, 244339646708, 938255682551, 3608668388957, 13900021844558, 53614340398327, 207062143625711 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Turning over will not create a new bracelet. Permuting the colors of the beads will not change the 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

Andrew Howroyd, Table of n, a(n) for n = 0..200

FORMULA

Use de Bruijn's generalization of Polya's enumeration theorem as discussed in reference.

a(n) = Sum_{k=1..4} A152176(n, k) for n > 0. - Andrew Howroyd, Oct 25 2019

CROSSREFS

Cf. A056292, A152176.

Sequence in context: A323067 A140108 A034295 * A072534 A056292 A106125

Adjacent sequences:  A056351 A056352 A056353 * A056355 A056356 A056357

KEYWORD

nonn

AUTHOR

Marks R. Nester

EXTENSIONS

a(0)=1 prepended and terms a(26) and beyond from Andrew Howroyd, Oct 25 2019

STATUS

approved

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Last modified July 2 08:02 EDT 2020. Contains 335398 sequences. (Running on oeis4.)