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

Author

Marks R. Nester

Keywords

• nonn

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]

Crossrefs

Cf. A056317.

Formula

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