

A056519


Number of primitive (period n) periodic palindromic structures using exactly three different symbols.


4



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, 128946888, 193448101, 387037370, 580606145, 1161485370
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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

Andrew Howroyd, Table of n, a(n) for n = 1..200


FORMULA

a(n) = A056514(n)  A056513(n).
Moebius transform of A056509.  Andrew Howroyd, Oct 01 2019


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, A056509, A056513, A056514.
Sequence in context: A041747 A180134 A192727 * A295972 A333405 A063445
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
Terms a(36) and beyond from Andrew Howroyd, Oct 01 2019


STATUS

approved



