

A056503


Number of periodic palindromic structures of length n using a maximum of two different symbols.


5



1, 2, 2, 4, 4, 7, 8, 14, 16, 26, 32, 51, 64, 100, 128, 198, 256, 392, 512, 778, 1024, 1552, 2048, 3091, 4096, 6176, 8192, 12324, 16384, 24640, 32768, 49222, 65536, 98432, 131072, 196744, 262144, 393472, 524288, 786698, 1048576, 1573376, 2097152, 3146256, 4194304
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OFFSET

1,2


COMMENTS

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


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..45.


FORMULA

No formula known  terms found by computer search.


CROSSREFS

Cf. A016116, A285012.
Sequence in context: A222738 A005308 A151532 * A256217 A055636 A206559
Adjacent sequences: A056500 A056501 A056502 * A056504 A056505 A056506


KEYWORD

nonn


AUTHOR

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


EXTENSIONS

a(17)a(45) from Andrew Howroyd, Apr 07 2017


STATUS

approved



