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A026306 a(n) = T(2n,n+1), where T is the array in A026300. 0

%I

%S 0,2,12,69,392,2235,12804,73710,426192,2473704,14405800,84137130,

%T 492652824,2891110235,16999928820,100136858625,590778928800,

%U 3490370847876,20647839813048,122287764072938,725023671281520,4302720916638417

%N a(n) = T(2n,n+1), where T is the array in A026300.

%F g.f. A(x)=(1/B(x))'-1, where B(x) g.f. of A006605.

%F 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

%e G.f. = 2*x + 12*x^2 + 69*x^3 + 392*x^4 + 2235*x^5 + 12804*x^6 + 73710*x^7 + ...

%o (Maxima)

%o 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

%K nonn

%O 0,2

%A _Clark Kimberling_

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Last modified October 28 17:59 EDT 2021. Contains 348329 sequences. (Running on oeis4.)