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A056318 Number of primitive (aperiodic) reversible strings with n beads using exactly two different colors. 1
0, 1, 4, 7, 18, 29, 70, 126, 266, 507, 1054, 2037, 4158, 8183, 16488, 32760, 65790, 131026, 262654, 524265, 1049524, 2097119, 4196350, 8388450, 16781292, 33554367, 67116784, 134217657, 268451838 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

A string and its reverse are considered to be equivalent. Identical to A045625 for n>1.

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..29.

FORMULA

Sum mu(d)*A056309(n/d) where d|n.

CROSSREFS

Cf. A045625.

Sequence in context: A318025 A005509 A147366 * A011948 A256216 A285462

Adjacent sequences:  A056315 A056316 A056317 * A056319 A056320 A056321

KEYWORD

nonn

AUTHOR

Marks R. Nester

STATUS

approved

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Last modified August 19 08:17 EDT 2019. Contains 326115 sequences. (Running on oeis4.)