A056274 Number of primitive (aperiodic) word structures of length n using a 3-ary alphabet.

1, 1, 4, 12, 40, 116, 364, 1080, 3276, 9800, 29524, 88440, 265720, 796796, 2391440, 7173360, 21523360, 64566684, 193710244, 581120880, 1743391832, 5230147076, 15690529804, 47071499760, 141214768200

Offset

1,3

Comments

Permuting the alphabet will not change a word structure. Thus aabc and bbca have the same 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..25.

Formula

Sum mu(d)*A007051(n/d-1) where d|n and n>0.

Crossrefs

Cf. A054718.

Sequence in context: A344122 A328533 A265127 * A335806 A058353 A104525

Adjacent sequences: A056271 A056272 A056273 * A056275 A056276 A056277

Keyword

nonn

Author

Marks R. Nester

Status

approved