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%I #2 Mar 30 2012 18:37:07
%S 1,9,27,0,-81,243,0,-2916,10935,0,-168399,682344,0,-11711385,49364964,
%T 0,-900438201,3887490915,0,-73729998576,323480165085,0,-6303914878248,
%U 27978933759300,0,-556251967191492,2490404893915293,0,-50276620111538700,226626845346291663,0
%N G.f. A(x) satisfies: A(x) = 1 + 9x*A(x)^(1/3).
%F a(n) = -9^n*binomial(n/3,n)/(2n/3 - 1).
%o (PARI) a(n)=9^n*binomial(n/3,n)/(1-2*n/3)
%Y Cf. A135863, A135866.
%K sign
%O 0,2
%A _Paul D. Hanna_, Dec 02 2007