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A056276
Number of primitive (aperiodic) word structures of length n using a 5-ary alphabet.
0
1, 1, 4, 13, 51, 196, 854, 3830, 17997, 86419, 422004, 2079260, 10306751, 51263086, 255514299, 1275160060, 6368612301, 31821454413, 159042661904, 795019250650, 3974515029793, 19870830290476, 99348921288654, 496728909635860, 2483597478617750, 12417846151236799
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]
FORMULA
a(n) = Sum_{d|n} mu(d)*A056272(n/d).
CROSSREFS
Sequence in context: A219579 A300122 A149461 * A144035 A056277 A082951
KEYWORD
nonn
STATUS
approved