

A056510


Number of periodic palindromic structures of length n using exactly four different symbols.


3



0, 0, 0, 0, 0, 1, 1, 7, 10, 43, 65, 220, 350, 1059, 1701, 4803, 7770, 21105, 34105, 90248, 145750, 379391, 611501, 1573432, 2532530, 6465473, 10391745, 26379908, 42355950, 107091559, 171798901, 433093459, 694337290, 1746630985, 2798806985, 7029341790, 11259666950
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OFFSET

1,8


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) = A056505(n)  A056504(n).
Inverse Moebius transform of A056521.  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 4 of A285012.
Cf. A056473, A056504, A056505, A056521.
Sequence in context: A258284 A099579 A056521 * A013398 A013493 A166661
Adjacent sequences: A056507 A056508 A056509 * A056511 A056512 A056513


KEYWORD

nonn


AUTHOR

Marks R. Nester


EXTENSIONS

Corrected by T. D. Noe, Oct 25 2006
a(17)a(30) from Andrew Howroyd, Apr 07 2017
Terms a(31) and beyond from Andrew Howroyd, Oct 01 2019


STATUS

approved



