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Search: id:A117376
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A117376 Expansion of 1/((1-3x*c(x))(1-x^2*c(x))), c(x) the g.f. of A000108. +0
2
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; listen)
OFFSET

0,2

COMMENT

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: A037583 A093834 A033887 this_sequence A102287 A006225 A100588

Adjacent sequences: A117373 A117374 A117375 this_sequence A117377 A117378 A117379

KEYWORD

easy,nonn

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Mar 10 2006

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.


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