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 A056492 Number of periodic palindromes using exactly six different symbols. 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,10 REFERENCES M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. LINKS Index to sequences with linear recurrences with constant coefficients, signature (1,20,-20,-155,155,580,-580,-1044,1044,720,-720). FORMULA 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] EXAMPLE For example, aaabbb is not a (finite) palindrome but it is a periodic palindrome. CROSSREFS Cf. A056457. Sequence in context: A076205 A048978 A056502 * A158308 A205738 A112536 Adjacent sequences:  A056489 A056490 A056491 * A056493 A056494 A056495 KEYWORD nonn,easy AUTHOR Marks R. Nester (nesterm(AT)dpi.qld.gov.au) STATUS approved

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