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A056492
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Number of periodic palindromes using exactly six different symbols.
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1
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0, 0, 0, 0, 0, 0, 0, 0, 0, 360, 720, 7920, 15120, 103320, 191520, 1048320, 1905120, 9170280, 16435440, 72833040, 129230640, 541130040, 953029440, 3832187040, 6711344640, 26192766600, 45674188560
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OFFSET
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1,10
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REFERENCES
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M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia.
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LINKS
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Table of n, a(n) for n=1..27.
Index to sequences with linear recurrences with constant coefficients, signature (1,20,-20,-155,155,580,-580,-1044,1044,720,-720).
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FORMULA
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a(n) = 2*A056346(n)-A056286(n).
G.f.: 360*x^10*(x+1)/((x-1)*(2*x-1)*(2*x+1)*(2*x^2-1)*(3*x^2-1)*(5*x^2-1)*(6*x^2-1)). [Colin Barker, Jul 08 2012]
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EXAMPLE
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For example, aaabbb is not a (finite) palindrome but it is a periodic palindrome.
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CROSSREFS
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Cf. A056457.
Sequence in context: A076205 A048978 A056502 * A158308 A205738 A112536
Adjacent sequences: A056489 A056490 A056491 * A056493 A056494 A056495
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KEYWORD
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nonn,easy
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AUTHOR
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Marks R. Nester (nesterm(AT)dpi.qld.gov.au)
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STATUS
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approved
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