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%I #5 Mar 30 2012 18:37:27
%S 1,1,2,6,20,73,281,1124,4633,19547,84023,366695,1620513,7237034,
%T 32609389,148066067,676805101,3111807931,14381741533,66775448718,
%U 311332294182,1456999560630,6841841485578,32228152992893,152241706312812,721055062770213
%N G.f. satisfies: A(x) = 1 + Sum_{n>=1} x^n*A(x)^sigma(n), where sigma(n) = A000203(n) is the sum of divisors of n.
%e G.f.: A(x) = 1 + x + 2*x^2 + 6*x^3 + 20*x^4 + 73*x^5 + 281*x^6 +...
%e The g.f. satisfies:
%e A(x) = 1 + x*A(x) + x^2*A(x)^3 + x^3*A(x)^4 + x^4*A(x)^7 + x^5*A(x)^6 + x^6*A(x)^12 + x^7*A(x)^8 + x^8*A(x)^15 +...
%o (PARI) {a(n)=local(A=1+x);for(i=1,n,A=1+sum(m=1,n,x^m*(A+x*O(x^n))^sigma(m)));polcoeff(A,n)}
%K nonn
%O 0,3
%A _Paul D. Hanna_, Jul 02 2011
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