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A213906 G.f. satisfies: A(x) = x^2/(1-x) + A(A(x)). 1

%I

%S 1,1,2,3,7,14,36,85,226,577,1561,4158,11413,31200,86722,241227,677729,

%T 1908832,5411431,15386107,43949347,125896209,361904137,1043032250,

%U 3014490719,8732211825,25353395331,73759912892,215007439768,627844428958,1836466543942

%N G.f. satisfies: A(x) = x^2/(1-x) + A(A(x)).

%e G.f.: A(x) = x^2 + x^3 + 2*x^4 + 3*x^5 + 7*x^6 + 14*x^7 + 36*x^8 + 85*x^9 +...

%e where

%e A(A(x)) = x^4 + 2*x^5 + 6*x^6 + 13*x^7 + 35*x^8 + 84*x^9 + 225*x^10 +...

%o (PARI) {a(n)=local(A=x^2+x^3);for(i=1,n,A=x^2/(1-x+x*O(x^n))+subst(A,x,A+x*O(x^n)));polcoeff(A,n)}

%o for(n=2,40,print1(a(n),", "))

%Y Cf. A213905.

%K nonn

%O 2,3

%A _Paul D. Hanna_, Jun 24 2012

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Last modified July 8 19:20 EDT 2020. Contains 335524 sequences. (Running on oeis4.)