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A056275
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Number of primitive (aperiodic) word structures of length n using a 4-ary alphabet.
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1
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1, 1, 4, 13, 50, 181, 714, 2780, 11046, 43895, 175274, 699875, 2798250, 11188191, 44747380, 178970560, 715860650, 2863365834, 11453377194, 45813202675, 183252461532, 733008625151, 2932033104554, 11728127521060
(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)*A007581(n/d-1) where d|n and n>0.
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CROSSREFS
| Cf. A054719.
Sequence in context: A149453 A149454 A101125 * A149455 A105968 A149456
Adjacent sequences: A056272 A056273 A056274 * A056276 A056277 A056278
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KEYWORD
| nonn
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AUTHOR
| Marks R. Nester (nesterm(AT)dpi.qld.gov.au)
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