A056490 - OEIS

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A056490

Number of periodic palindromes using exactly four different symbols.

0, 0, 0, 0, 0, 12, 24, 132, 240, 900, 1560, 4980, 8400, 24612, 40824, 113652, 186480, 502500, 818520, 2158260, 3498000, 9087012, 14676024, 37728372, 60780720, 155091300, 249401880, 632972340, 1016542800 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,6`
	REFERENCES	`M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia.`
	FORMULA	`2*A056344(n)-A056284(n).`
	EXAMPLE	`For example, aaabbb is not a (finite) palindrome but it is a periodic palindrome.`
	CROSSREFS	`Cf. A056455.` `Sequence in context: A109745 A051385 A056500 * A130163 A002167 A154268` `Adjacent sequences: A056487 A056488 A056489 * A056491 A056492 A056493`
	KEYWORD	`nonn`
	AUTHOR	`Marks R. Nester (nesterm(AT)dpi.qld.gov.au)`

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Last modified February 14 18:47 EST 2012. Contains 205663 sequences.