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A056275 Number of primitive (aperiodic) word structures of length n using a 4-ary alphabet. 1
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; text; internal format)
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..24.

FORMULA

sum mu(d)*A007581(n/d-1) where d|n and n>0.

CROSSREFS

Cf. A054719.

Sequence in context: A284336 A230081 A299699 * A149455 A105968 A149456

Adjacent sequences:  A056272 A056273 A056274 * A056276 A056277 A056278

KEYWORD

nonn

AUTHOR

Marks R. Nester

STATUS

approved

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Last modified August 10 01:45 EDT 2020. Contains 336363 sequences. (Running on oeis4.)