

A056477


Number of primitive (aperiodic) palindromic structures using a maximum of three different symbols.


4



1, 0, 1, 1, 4, 3, 13, 12, 39, 36, 121, 116, 364, 351, 1088, 1080, 3280, 3237, 9841, 9800, 29510, 29403, 88573, 88440, 265716, 265356, 797121, 796796, 2391484, 2390352, 7174453
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OFFSET

1,5


COMMENTS

Permuting the symbols will not change the 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..31.


FORMULA

a(n) = Sum mu(d)*b(n/d) where dn and b() = 1, 1, 2, 2, 5, 5, 14, 14, 41, 41, 122, 122, ... (A007051 repeated).


CROSSREFS

Cf. A056459.
Sequence in context: A169706 A120340 A082018 * A105200 A088933 A019136
Adjacent sequences: A056474 A056475 A056476 * A056478 A056479 A056480


KEYWORD

nonn


AUTHOR

Marks R. Nester (nesterm(AT)dpi.qld.gov.au)


STATUS

approved



