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A203014
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G.f. satisfies: A(x) = Sum_{n>=0} x^n * (2*A(x)^n - 1)^n.
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4
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1, 1, 3, 15, 93, 655, 5025, 40995, 350665, 3116083, 28588541, 269632839, 2606374433, 25766661303, 260133432037, 2679336234403, 28138284922321, 301224023801747, 3286962740398689, 36567211855460123, 414883492490364865, 4802747139352783619, 56754591674540964917
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OFFSET
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0,3
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LINKS
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FORMULA
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G.f. satisfies: A(x) = Sum_{n>=0} 2^n*x^n * A(x)^(n^2)/(1 + x*A(x)^n)^(n+1).
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EXAMPLE
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G.f.: A(x) = 1 + x + 3*x^2 + 15*x^3 + 93*x^4 + 655*x^5 + 5025*x^6 +...
where the g.f. satisfies following series identity:
A(x) = 1 + (2*A(x)-1)*x + (2*A(x)^2-1)^2*x^2 + (2*A(x)^3-1)^3*x^3 + (2*A(x)^4-1)^4*x^4 +...
A(x) = 1/(1+x) + 2*x*A(x)/(1+x*A(x))^2 + 2^2*x^2*A(x)^4/(1+x*A(x)^2)^3 + 2^3*x^3*A(x)^9/(1+x*A(x)^3)^4 + 2^4*x^4*A(x)^16/(1+x*A(x)^4)^5 +...
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PROG
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(PARI) {a(n)=local(A=1+x); for(i=1, n, A=sum(k=0, n, (2*A^k-1+x*O(x^n))^k*x^k)); polcoeff(A, n)}
(PARI) {a(n)=local(A=1+x); for(i=1, n, A=sum(k=0, n, 2^k*A^(k^2)*x^k/(1+A^k*x+x*O(x^n))^(k+1) )); polcoeff(A, n)}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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