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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
 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; text; internal format)
 OFFSET 0,2 COMMENTS Diagonal sums of number triangle A117375. LINKS 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: A033887 A291653 A183804 * A264037 A151318 A151212 Adjacent sequences:  A117373 A117374 A117375 * A117377 A117378 A117379 KEYWORD easy,nonn AUTHOR Paul Barry, Mar 10 2006 STATUS approved

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Last modified April 6 12:19 EDT 2020. Contains 333273 sequences. (Running on oeis4.)