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URL: https://oeis.org/A056519

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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
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
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.
Sequence in context: A041747 A180134 A192727 * A295972 A333405 A063445
KEYWORD
nonn
EXTENSIONS
a(17)-a(35) from Andrew Howroyd, Apr 08 2017
Terms a(36) and beyond from Andrew Howroyd, Oct 01 2019
STATUS
approved