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G.f. satisfies: A(A(x)) = A(x) + A(x^2).
0

%I #3 Mar 30 2012 18:37:10

%S 1,1,-2,10,-62,466,-4004,37774,-383042,4120768,-46601144,550296628,

%T -6751738736,85742962300,-1123702072256,15161509999324,

%U -210202294372118,2989858353554554,-43572404751879032,649889656256427742,-9911173481433673436

%N G.f. satisfies: A(A(x)) = A(x) + A(x^2).

%e G.f.: A(x) = x + x^2 - 2*x^3 + 10*x^4 - 62*x^5 + 466*x^6 - 4004*x^7 +-...

%e A(A(x)) = x + 2*x^2 - 2*x^3 + 11*x^4 - 62*x^5 + 464*x^6 - 4004*x^7 +-...

%o (PARI) {a(n)=local(A=x+x^2);for(i=0,n, A=x+subst(A,x,serreverse(A+x*O(x^n))^2));polcoeff(A,n)}

%K sign

%O 1,3

%A _Paul D. Hanna_, Jun 10 2008