A056318 Number of primitive (aperiodic) reversible strings with n beads using exactly two different colors.

0, 1, 4, 7, 18, 29, 70, 126, 266, 507, 1054, 2037, 4158, 8183, 16488, 32760, 65790, 131026, 262654, 524265, 1049524, 2097119, 4196350, 8388450, 16781292, 33554367, 67116784, 134217657, 268451838

Offset

1,3

Comments

A string and its reverse are considered to be equivalent. Identical to A045625 for n>1.

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..29.

Formula

Sum mu(d)*A056309(n/d) where d|n.

Crossrefs

Cf. A045625.

Sequence in context: A318025 A005509 A147366 * A011948 A256216 A285462

Adjacent sequences: A056315 A056316 A056317 * A056319 A056320 A056321

Keyword

nonn

Author

Marks R. Nester

Status

approved