A133443 - OEIS

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A133443

a(n)=sum{k=0..n, C(n,floor(k/2))*(-1)^k*3^(n-k)}.

1, 2, 8, 24, 84, 272, 920, 3040, 10180, 33840, 112968, 376224, 1254696, 4181088, 13939248, 46459584, 154873860, 516229040, 1720795880 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	COMMENTS	`Hankel transform is 4^n . Second binomial transform is A076035 .`
	FORMULA	`a(n)=Sum{k, 0<=k<=n} A053121(n,k)A015518(k+1) = (-1)^nA127362(n) . G.f.: (1/sqrt(1-4x^2))(1-xc(x^2))/(1-3x*c(x^2)), where c(x) is the g.f. of Catalan numbers A000108 .`
	CROSSREFS	`Sequence in context: A063727 A085449 A127362 * A094038 A007223 A106189` `Adjacent sequences: A133440 A133441 A133442 * A133444 A133445 A133446`
	KEYWORD	`nonn`
	AUTHOR	`Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 26 2007, Dec 07 2007`

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Last modified February 15 05:45 EST 2012. Contains 205694 sequences.