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%I #5 Mar 30 2012 18:37:29
%S 1,1,4,16,77,389,2128,12019,70185,418788,2544938,15687842,97871618,
%T 616729500,3919686231,25096525793,161723865118,1048085548563,
%U 6826585371618,44664343473618,293407529533947,1934484748893113,12796683165889635,84906535878961845
%N G.f. satisfies A(x) = 1/Product_{n>=1} (1 - x^n*A(x^n)^2).
%e G.f.: A(x) = 1 + x + 4*x^2 + 16*x^3 + 77*x^4 + 389*x^5 + 2128*x^6 +...
%e where
%e A(x) = 1/((1 - x*A(x)^2) * (1 - x^2*A(x^2)^2) * (1 - x^3*A(x^3)^2) *...).
%o (PARI) {a(n)=local(A=1+x); for(i=1, n, A=1/prod(k=1, n, (1-x^k*subst(A,x,x^k+x*O(x^n))^2))); polcoeff(A, n)}
%Y Cf. A050383, A196191.
%K nonn
%O 0,3
%A _Paul D. Hanna_, Sep 28 2011
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