A056335 Number of primitive (aperiodic) reversible string structures with n beads using a maximum of six different colors.

1, 1, 3, 9, 31, 112, 466, 2124, 10476, 55058, 301632, 1703989, 9819215, 57364723, 338134486, 2005132504, 11937364183, 71254885362, 426063226936, 2550552259119, 15280103806730, 91588103894781

Offset

1,3

Comments

A string and its reverse are considered to be equivalent. Permuting the colors 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

Table of n, a(n) for n=1..22.

Formula

Sum mu(d)*A056325(n/d) where d|n.

Crossrefs

Cf. A056317.

Sequence in context: A101473 A056334 A063032 * A276549 A049188 A049165

Adjacent sequences: A056332 A056333 A056334 * A056336 A056337 A056338

Keyword

nonn

Author

Marks R. Nester

Status

approved