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A056274
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Number of primitive (aperiodic) word structures of length n using a 3-ary alphabet.
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1
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Permuting the alphabet will not change a word structure. Thus aabc and bbca have the same structure.
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REFERENCES
| M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia.
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FORMULA
| Sum mu(d)*A007051(n/d-1) where d|n and n>0.
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CROSSREFS
| Cf. A054718.
Sequence in context: A149330 A149331 A009532 * A058353 A104525 A126986
Adjacent sequences: A056271 A056272 A056273 * A056275 A056276 A056277
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KEYWORD
| nonn
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AUTHOR
| Marks R. Nester (nesterm(AT)dpi.qld.gov.au)
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