A056340 Number of primitive (aperiodic) reversible string structures with n beads using exactly six different colors.

0, 0, 0, 0, 0, 1, 12, 142, 1346, 11511, 89974, 662673, 4662574, 31724723, 210361046, 1367510184, 8752976610, 55343946628, 346541488998, 2153041576027, 13292844257186, 81652683460145, 499484958151630

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

Column 6 of A276544.

Cf. A056322.

Formula

A056335(n)-A056334(n).