id:A103368 - OEIS Search Results

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Expansion of (1+x)/(1+x^2+x^4).

+0
2

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

	OFFSET	`0,1`
	COMMENT	`The positive sequence is a(n)=(cos(2pin/3+pi/3)/6+sqrt(3)sin(2pin/3+pi/3)/6 -sqrt(3)cos(pin/3+pi/6)/6+sin(pin/3+pi/6)/2+2/3, with g.f. (1+x+x^2+x^4)/(1-x^6).`
	FORMULA	`a(n)=sum{k=0..floor(n/2), binomial(k, floor(n/2)-k)(-1)^k); a(n)=-cos(2pin/3+pi/3)/2+sqrt(3)sin(2pin/3+pi/3)/6+sqrt(3)cos(pin/3+pi/6)/2+sin(pin/3+pi/6)/2.`
	CROSSREFS	`Adjacent sequences: A103365 A103366 A103367 this_sequence A103369 A103370 A103371` `Sequence in context: A130657 A084846 A130093 this_sequence A055132 A128408 A121802`
	KEYWORD	`easy,sign`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Feb 02 2005`

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Last modified October 11 13:47 EDT 2008. Contains 144830 sequences.

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