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%I #6 Jan 28 2020 15:19:06
%S 1,2,18,284,6680,211398,8439235,407247048,23056215138,1498169721930,
%T 109876657252604,8976437481923520,808257688877060396,
%U 79516093326076500590,8485004019719253675540,976009472808194554659440
%N Central terms of triangle A127126; a(n) = A127126(2n,n).
%C a(n) is divisible by (n+1): a(n)/(n+1) = A127135(n).
%H G. C. Greubel, <a href="/A127134/b127134.txt">Table of n, a(n) for n = 0..50</a>
%t T[n_, k_]:= T[n, k]= If[k==n, 1, Coefficient[(1 +x*Sum[x^(r-k-1)*Sum[T[r, c], {c,k+1,r}], {r,k+1,n}] +x^(n+1))^(k+1), x, n-k]]; Table[T[2*n, n], {n,0,20}] (* _G. C. Greubel_, Jan 28 2020 *)
%Y Cf. A127126, A127127, A127128, A127129, A127130, A127131, A127132, A127133, A127135.
%K nonn
%O 0,2
%A _Paul D. Hanna_, Jan 05 2007