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A056519 Number of primitive (period n) periodic palindromic structures using exactly three different symbols. 1
0, 0, 0, 1, 1, 5, 6, 18, 25, 63, 90, 202, 301, 650, 965, 2016, 3025, 6220, 9330, 18970, 28495, 57650, 86526, 174210, 261624, 525693, 788945, 1582462, 2375101, 4759482, 7141686, 14300976, 21457735, 42951825, 64439003 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

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..35.

FORMULA

A056514(n)-A056513(n).

EXAMPLE

For example, aaabbb is not a (finite) palindrome but it is a periodic palindrome. Permuting the symbols will not change the structure.

CROSSREFS

Column 3 of A285037.

Cf. A056482.

Sequence in context: A041747 A180134 A192727 * A295972 A063445 A257331

Adjacent sequences:  A056516 A056517 A056518 * A056520 A056521 A056522

KEYWORD

nonn

AUTHOR

Marks R. Nester

EXTENSIONS

a(17)-a(35) from Andrew Howroyd, Apr 08 2017

STATUS

approved

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Last modified July 17 02:56 EDT 2019. Contains 325092 sequences. (Running on oeis4.)