id:A077903 - OEIS Search Results

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

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1, 0, 2, -3, 6, -12, 25, -48, 98, -195, 390, -780, 1561, -3120, 6242, -12483, 24966, -49932, 99865, -199728, 399458, -798915, 1597830, -3195660, 6391321, -12782640, 25565282, -51130563, 102261126, -204522252, 409044505, -818089008, 1636178018, -3272356035, 6544712070 (list; graph; listen)

	OFFSET	`0,3`
	COMMENT	`Convolution of A010892(n) and (-1)^n*A001045(n+1). The positive sequence has g.f. 1/((1-x-2x^2)(1+x+x^2)). This is the convolution of A001045(n+1) and A049347(n). - Paul Barry (pbarry(AT)wit.ie), May 19 2004`
	FORMULA	`G.f. : 1/((1+x-2x^2)(1-x+x^2)); a(n)=sum{k=0..n, (2(-2)^k/3+1/3)2sin(pi(n-k)/3+pi/3)/sqrt(3)}; a(n)=2^(n+3)cos(pin)/21+8sqrt(3)cos(pin/3+pi/6)/63+4sqrt(3)sin(pin/3+pi/3)/63 +2sqrt(3)sin(pin/3)/9+1/3; - Paul Barry (pbarry(AT)wit.ie), May 19 2004`
	CROSSREFS	`Sequence in context: A035055 A119559 A045761 this_sequence A038086 A032305 A032218` `Adjacent sequences: A077900 A077901 A077902 this_sequence A077904 A077905 A077906`
	KEYWORD	`sign`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com), Nov 17 2002`

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Last modified December 20 13:54 EST 2009. Contains 171081 sequences.

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