A117376 - OEIS

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A117376

Expansion of 1/((1-3x*c(x))(1-x^2*c(x))), c(x) the g.f. of A000108.

1, 3, 13, 55, 240, 1057, 4688, 20879, 93250, 417272, 1869725, 8386137, 37640961, 169042436, 759470361, 3413223919, 15343588991, 68988110756, 310233741889, 1395268187372, 6275807975664, 28230370862051, 126996552221811 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	COMMENTS	`Diagonal sums of number triangle A117375.`
	FORMULA	`a(n)=sum{k=0..floor(n/2), [k<=n-k]sum{j=0..n-k, (j/(n-k-j))C(2n-k-j,n-k-j)[k<=j]*3^(j-k)}}`
	CROSSREFS	`Sequence in context: A093834 A033887 A183804 * A151318 A151212 A151213` `Adjacent sequences: A117373 A117374 A117375 * A117377 A117378 A117379`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Mar 10 2006`

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Last modified February 15 12:21 EST 2012. Contains 205785 sequences.