A056315 Number of primitive (aperiodic) reversible strings with n beads using a maximum of four different colors.

4, 6, 36, 126, 540, 2034, 8316, 32760, 131544, 524250, 2099196, 8388450, 33562620, 134217594, 536903100, 2147483520, 8590065660, 34359735816, 137439477756, 549755813250, 2199025344348, 8796093020154

Offset

1,1

Comments

A string and its reverse are considered to be equivalent.

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)*A032121(n/d) where d|n.

Crossrefs

Column 4 of A284871.

Cf. A045625, A056314.

Sequence in context: A222502 A092187 A092765 * A103234 A074061 A125081

Adjacent sequences: A056312 A056313 A056314 * A056316 A056317 A056318

Keyword

nonn

Author

Marks R. Nester

Status

approved