A127630 - OEIS

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A127630

Expansion of (1+x-x^2-x^3)/(1+x^2)^2.

1, 1, -3, -3, 5, 5, -7, -7, 9, 9, -11, -11, 13, 13, -15, -15, 17, 17, -19, -19, 21, 21, -23, -23, 25, 25, -27, -27, 29, 29, -31, -31, 33, 33, -35, -35, 37, 37, -39, -39, 41, 41, -43, -43, 45, 45, -47, -47, 49, 49, -51, -51, 53, 53, -55, -55 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,3`
	COMMENTS	`Hankel transform of A045621(n+1).`
	FORMULA	`a(n)=(2^C(n,2))(2floor(n/2)+1)`
	CROSSREFS	`Cf. A109613.` `Sequence in context: A177691 A117767 A063196 * A109613 A175298 A073737` `Adjacent sequences: A127627 A127628 A127629 * A127631 A127632 A127633`
	KEYWORD	`easy,sign`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Jan 20 2007`

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Last modified February 14 23:53 EST 2012. Contains 205689 sequences.