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A056493 Number of primitive (period n) periodic palindromes using a maximum of two different symbols. 3
2, 1, 2, 3, 6, 7, 14, 18, 28, 39, 62, 81, 126, 175, 246, 360, 510, 728, 1022, 1485, 2030, 3007, 4094, 6030, 8184, 12159, 16352, 24381, 32766, 48849, 65534, 97920, 131006, 196095, 262122, 392364, 524286, 785407, 1048446, 1571310, 2097150, 3143497 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For example, aaabbb is not a (finite) palindrome but it is a periodic palindrome.

Also aperiodic necklaces (Lyndon words) that are the same when turned over.

REFERENCES

M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia.

LINKS

Table of n, a(n) for n=1..42.

Index entries for sequences related to Lyndon words

FORMULA

Sum mu(d)*A029744(n/d) where d divides n.

CROSSREFS

Cf. A056458.

Sequence in context: A108618 A097719 A249050 * A001371 A001037 A122086

Adjacent sequences:  A056490 A056491 A056492 * A056494 A056495 A056496

KEYWORD

nonn

AUTHOR

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

EXTENSIONS

More terms and additional comments from Christian G. Bower, Jun 22 2000

STATUS

approved

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Last modified December 21 10:46 EST 2014. Contains 252305 sequences.