A157143 - OEIS

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A157143

A transform of the Motzkin numbers.

1, -1, -1, 0, 2, 1, -1, -4, -2, 5, 11, 0, -21, -24, 18, 68, 42, -100, -203, -17, 428, 521, -340, -1544, -1019, 2252, 4892, 606, -10297, -13331, 7821, 39310, 28028, -56893, -130394, -22239, 272991, 370641, -193874, -1081694, -821669 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,5`
	COMMENTS	`Hankel transform is A157144.`
	FORMULA	`G.f.: (1-x)/(1+x^2+x^3)c((x/(1+x^2+x^3))^2), c(x) the g.f. of A000108.` `a(n)=sum{k=0..n, (-1)^C(n-k+1,2)C(floor((n-k)/2),k)*A001006(k)}.`
	CROSSREFS	`Sequence in context: A177276 A123199 A157125 * A112096 A026725 A026758` `Adjacent sequences: A157140 A157141 A157142 * A157144 A157145 A157146`
	KEYWORD	`easy,sign`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Feb 24 2009`

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Last modified February 15 17:45 EST 2012. Contains 205833 sequences.