id:A108262 - OEIS Search Results

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Second order recursive series having the property that the product of any two adjacent terms equals 4 times a triangular number. That is a(n)*a(n+1)= 4*T(c) = 2c(c+1), where c = the term a(n+1) of related series A108261.

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3, 8, 39, 220, 1275, 7424, 43263, 252148, 1469619, 8565560, 49923735, 290976844, 1695937323, 9884647088, 57611945199 (list; graph; listen)

	OFFSET	`0,1`
	LINKS	`K. J. Ramsey, RecursiveSeriesProblem`
	FORMULA	`a(n) = 6a(n-1) - a(n-2) -6` `a(n)= 3/2+(1/4)[3+2sqrt(2)]^n+(1/4)[3-2*sqrt(2)]^n , with n>=0 - Paolo P. Lava (ppl(AT)spl.at), Jun 25 2008`
	EXAMPLE	`a(5)=1275`
	CROSSREFS	`Cf. A108261.` `Sequence in context: A099030 A106558 A065914 this_sequence A034892 A072687 A110561` `Adjacent sequences: A108259 A108260 A108261 this_sequence A108263 A108264 A108265`
	KEYWORD	`nonn`
	AUTHOR	`Kenneth John Ramsey (RamseyKK2(AT)aol.com), May 29 2005`

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Last modified July 26 23:19 EDT 2008. Contains 142293 sequences.

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