A138340 - OEIS

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A138340

Expansion of (1-8x)/(1-4x+16x^2).

1, -4, -32, -64, 256, 2048, 4096, -16384, -131072, -262144, 1048576, 8388608, 16777216, -67108864, -536870912, -1073741824, 4294967296, 34359738368, 68719476736, -274877906944, -2199023255552, -4398046511104, 17592186044416 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	COMMENTS	`abs(a(n))=2^A047267(n).`
	FORMULA	`a(n):=24^n(cos(pi(n+1)/3)-sqrt(3)sin(pi(n+1))/3);` `a(n)=4^nSum_{k, 0<=k<=n} A121314(n,k)(-1)^k3^(n-k). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 01 2008]` `a(n)=A128018(n)2^n. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 14 2008]`
	CROSSREFS	`Sequence in context: A114076 A078092 A076137 * A113250 A012036 A153794` `Adjacent sequences: A138337 A138338 A138339 * A138341 A138342 A138343`
	KEYWORD	`easy,sign`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Mar 15 2008`

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Last modified February 14 15:39 EST 2012. Contains 205635 sequences.