

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.


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



