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

1,7

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..23.

Formula

A056335(n)-A056334(n).

Crossrefs

Column 6 of A276544.

Cf. A056322.

Sequence in context: A061636 A266177 A135326 * A056330 A158516 A163448

Adjacent sequences: A056337 A056338 A056339 * A056341 A056342 A056343

Keyword

nonn

Author

Marks R. Nester

Status

approved