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%I #5 Nov 28 2016 10:36:05
%S 1,1,1,3,6,21,54,195,573,2086,6646,24289,81540,299136,1040262,3832923,
%T 13660698,50572983,183450064,682447378,2507959846,9374078232,
%U 34791088014,130624080993,488542321116,1841890385196,6931198308924
%N Expansion of 2/(3-sqrt(3-2*sqrt(1-4x))).
%C Row sums of number triangle A112519.
%F a(n)=sum{k=0..n, sum{j=0..n, (k/n)(-1)^(j-k)C(2n-j-1, n-j)C(2j-k-1, j-k)}}.
%t CoefficientList[Series[2/(3-Sqrt[3-2*Sqrt[1-4x]]),{x,0,30}],x] (* _Harvey P. Dale_, Nov 28 2016 *)
%K easy,nonn
%O 0,4
%A _Paul Barry_, Sep 09 2005
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