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A056314 Number of primitive (aperiodic) reversible strings with n beads using a maximum of three different colors. 4
3, 3, 15, 39, 132, 357, 1131, 3276, 9945, 29508, 88935, 265668, 798252, 2391441, 7177584, 21523320, 64579920, 193709763, 581160255, 1743392040, 5230264026, 15690529437, 47071855131, 141214764600 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A string and its reverse are considered to be equivalent.

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..24.

FORMULA

Sum mu(d)*A032120(n/d) where d|n.

CROSSREFS

Column 3 of A284871.

Cf. A045625.

Sequence in context: A035617 A126319 A165553 * A171379 A078631 A160639

Adjacent sequences:  A056311 A056312 A056313 * A056315 A056316 A056317

KEYWORD

nonn

AUTHOR

Marks R. Nester

STATUS

approved

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Last modified September 27 04:10 EDT 2021. Contains 347673 sequences. (Running on oeis4.)