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%I #6 Oct 15 2013 21:31:32
%S 1,1,2,6,26,164,1548,22612,527016,20075480,1272488296,136039530768,
%T 24791209794352,7767414503113808,4214117431305739680,
%U 3983248890848252043616,6594358097712974323610528,19210839739434953100591639104,98895926239537023373263092515008
%N G.f. satisfies: A(x) = Sum_{n>=0} x^n * Product_{k=0..n-1} A(2^k*x).
%e G.f.: A(x) = 1 + x + 2*x^2 + 6*x^3 + 26*x^4 + 164*x^5 +...
%e where
%e A(x) = 1 + x*A(x) + x^2*A(x)*A(2*x) + x^3*A(x)*A(2*x)*A(4*x) +...
%o (PARI) {a(n,r=1)=local(A=1+x);for(i=1,n,A=1+sum(m=1,n,r^m*x^m*prod(k=0,m-1,subst(A,x,2^k*x+x*O(x^n)))));polcoeff(A,n)}
%o for(n=0,20,print1(a(n),", "))
%Y Cf. A230316, A158888.
%K nonn
%O 0,3
%A _Paul D. Hanna_, May 19 2010
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