id:A115451 - OEIS Search Results

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

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1, 1, 2, 4, 9, 17, 34, 68, 137, 273, 546, 1092, 2185, 4369, 8738, 17476, 34953, 69905, 139810, 279620, 559241, 1118481, 2236962, 4473924, 8947849, 17895697, 35791394, 71582788, 143165577, 286331153, 572662306, 1145324612, 2290649225 (list; graph; listen)

	OFFSET	`0,3`
	COMMENT	`Signed version is A077931. Row sums of A115450.`
	FORMULA	`a(n)=a(n)=a(n-1)+a(n-2)+a(n-3)+2a(n-4); a(n)=sum{k=0..n, (2^(n-k+1)-1)(-1)^k}-sum{k=0..floor(n/2), (2^(n-2k)-1)(-1)^k}; a(n)=A000975(n+1)-A077854(n-1).`
	CROSSREFS	`Adjacent sequences: A115448 A115449 A115450 this_sequence A115452 A115453 A115454` `Sequence in context: A065026 A007502 A088039 this_sequence A077931 A136326 A059973`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Jan 22 2006`

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Last modified May 16 23:01 EDT 2008. Contains 139884 sequences.

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