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

Author

Marks R. Nester

Keywords

• nonn

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]

Crossrefs

Cf. A054718.

Formula

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