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A056315 Number of primitive (aperiodic) reversible strings with n beads using a maximum of four different colors. 3
4, 6, 36, 126, 540, 2034, 8316, 32760, 131544, 524250, 2099196, 8388450, 33562620, 134217594, 536903100, 2147483520, 8590065660, 34359735816, 137439477756, 549755813250, 2199025344348, 8796093020154 (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..22.

FORMULA

Sum mu(d)*A032121(n/d) where d|n.

CROSSREFS

Column 4 of A284871.

Cf. A045625, A056314.

Sequence in context: A222502 A092187 A092765 * A103234 A074061 A125081

Adjacent sequences:  A056312 A056313 A056314 * A056316 A056317 A056318

KEYWORD

nonn

AUTHOR

Marks R. Nester

STATUS

approved

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Last modified August 22 16:17 EDT 2019. Contains 326178 sequences. (Running on oeis4.)