id:A157143 - OEIS Search Results

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A transform of the Motzkin numbers.

+0
2

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; listen)

	OFFSET	`0,5`
	COMMENT	`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: A122517 A123199 A157125 this_sequence A112096 A026725 A026758` `Adjacent sequences: A157140 A157141 A157142 this_sequence A157144 A157145 A157146`
	KEYWORD	`easy,sign`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Feb 24 2009`

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Last modified December 18 21:37 EST 2009. Contains 171024 sequences.

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