id:A117413 - OEIS Search Results

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Expansion of (1-x^2)/(1-2x^2+4x^3+x^4).

+0
2

1, 0, 1, -4, 1, -12, 17, -24, 81, -104, 241, -508, 817, -1876, 3425, -6512, 13537, -24848, 49697, -97332, 185249, -368604, 710129, -1380872, 2709425, -5233656, 10232209, -19924140, 38689617, -75543460, 146843585, -285921248, 557171393, -1083673376, 2111184193, -4110111076 (list; graph; listen)

	OFFSET	`0,4`
	COMMENT	`Diagonal sums of number triangle A117411.`
	FORMULA	`a(n)=2a(n-2)-4a(n-3)-a(n-4); a(n)=sum{k=0..floor(n/2), sum{j=0..n-2k, C(n-k,k-j)C(j,n-2k)}(-4)^(n-2k)}.`
	CROSSREFS	`Sequence in context: A125105 A049424 A078219 this_sequence A105197 A089503 A019236` `Adjacent sequences: A117410 A117411 A117412 this_sequence A117414 A117415 A117416`
	KEYWORD	`easy,sign`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Mar 14 2006`

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Last modified July 23 17:35 EDT 2008. Contains 142285 sequences.

AT&T Labs Research