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 A107589 G.f. satisfies: A(x) = 1 + Sum_{n>=1} x^n*A^(2^(n-1)). 3

%I

%S 1,1,2,5,15,52,205,921,4807,30288,243338,2636799,39930125,851799936,

%T 25433798924,1055317281976,60604557533320,4808635126697325,

%U 526853206940116357,79701484897115170371,16651360300285759198344

%N G.f. satisfies: A(x) = 1 + Sum_{n>=1} x^n*A^(2^(n-1)).

%e A = 1 + x*A + x^2*A^2 + x^3*A^4 + x^4*A^8 + x^5*A^16 +...

%e = 1 + (x + x^2 + 2*x^3 + 5*x^4 + 15*x^5 + 52*x^6 +...)

%e + (x^2 + 2*x^3 + 5*x^4 + 14*x^5 + 44*x^6 + 154*x^7 +...)

%e + (x^3 + 4*x^4 + 14*x^5 + 48*x^6 + 169*x^7 +...)

%e + (x^4 + 8*x^5 + 44*x^6 + 208*x^7 +...)

%e + (x^5 + 16*x^6 + 152*x^7 +...) +...

%o (PARI) {a(n)=local(A=1+x+x*O(x^n)); for(k=1,n,A=1+sum(j=1,n,x^j*A^(2^(j-1))));polcoeff(A,n)}

%K nonn

%O 0,3

%A _Paul D. Hanna_, May 17 2005

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Last modified May 16 07:59 EDT 2021. Contains 343939 sequences. (Running on oeis4.)