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 A026306 a(n) = T(2n,n+1), where T is the array in A026300. 0
 0, 2, 12, 69, 392, 2235, 12804, 73710, 426192, 2473704, 14405800, 84137130, 492652824, 2891110235, 16999928820, 100136858625, 590778928800, 3490370847876, 20647839813048, 122287764072938, 725023671281520, 4302720916638417 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS FORMULA g.f. A(x)=(1/B(x))'-1, where B(x) g.f. of A006605. a(n) = n*(Sum_{j=0..2*n+1} binomial(j,-3*n+2*j-1)*binomial(2*n+1,j)))/(2*n+1) - Vladimir Kruchinin, May 15 2014 EXAMPLE G.f. = 2*x + 12*x^2 + 69*x^3 + 392*x^4 + 2235*x^5 + 12804*x^6 + 73710*x^7 + ... PROG (Maxima) a(n):=(n*sum(binomial(j, -3*n+2*j-1)*binomial(2*n+1, j), j, 0, 2*n+1))/(2*n+1); Vladimir Kruchinin, May 15 2014 CROSSREFS Sequence in context: A245854 A078839 A243771 * A116398 A001542 A059229 Adjacent sequences:  A026303 A026304 A026305 * A026307 A026308 A026309 KEYWORD nonn AUTHOR STATUS approved

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Last modified September 23 20:42 EDT 2021. Contains 347617 sequences. (Running on oeis4.)