A087205 - OEIS

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A087205

a(n)=-2a(n-1)+4a(n-2), a(0)=1,a(1)=2.

1, 2, 0, 8, -16, 64, -192, 640, -2048, 6656, -21504, 69632, -225280, 729088, -2359296, 7634944, -24707072, 79953920, -258736128, 837287936, -2709520384, 8768192512, -28374466560, 91821703168, -297141272576, 961569357824, -3111703805952 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	COMMENTS	`Inverse binomial transform of A087204. a(n+2)=A085449(n)(-1)^(n+1); a(n+3)=A063727(n)(-1)^n.`
	FORMULA	`a(n)=(-1-sqrt(5))^n(1/2-3sqrt(5)/10)+(-1+sqrt(5))^n(1/2+3sqrt(5)/10).`
	CROSSREFS	`Cf. A084222.` `Sequence in context: A120555 A128063 A171552 * A062134 A002909 A118437` `Adjacent sequences: A087202 A087203 A087204 * A087206 A087207 A087208`
	KEYWORD	`easy,sign`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Aug 25 2003`

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Last modified February 15 17:43 EST 2012. Contains 205830 sequences.