id:A117569 - OEIS Search Results

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

+0
4

1, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0 (list; graph; listen)

	OFFSET	`0,1`
	COMMENT	`Row sums of A117568.`
	FORMULA	`G.f.: (1-x^3)/((1-x)(1+x^2)); a(n)=0^n+(1-(-1)^n)(cos(pin/2)+sin(pin/2))/2;` `a(n)=A101455(n), n>0. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 10 2008]`
	CROSSREFS	`Cf. A073097.` `Sequence in context: A080545 A141735 A073097 this_sequence A135528 A071040 A078387` `Adjacent sequences: A117566 A117567 A117568 this_sequence A117570 A117571 A117572`
	KEYWORD	`easy,sign`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Mar 29 2006`

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.

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