A056319 Number of primitive (aperiodic) reversible strings with n beads using exactly three different colors.

0, 0, 3, 18, 78, 270, 921, 2898, 9147, 27987, 85773, 259557, 785778, 2366892, 7128120, 21425040, 64382550, 193316685, 580372293, 1741819245, 5227115454, 15684238080, 47059266081, 141189599250

Offset

1,3

Comments

Each 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)*A056310(n/d) where d|n.

Crossrefs

Cf. A056314.

Sequence in context: A245580 A043008 A241628 * A056310 A309259 A308853

Adjacent sequences: A056316 A056317 A056318 * A056320 A056321 A056322

Keyword

nonn

Author

Marks R. Nester

Status

approved