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A213263
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G.f. satisfies: A(x) = x + A( A(x)^2/(1 + A(x)) ).
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2
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1, 1, 1, 2, 5, 12, 30, 80, 219, 609, 1724, 4953, 14388, 42193, 124768, 371602, 1113667, 3356017, 10162979, 30911457, 94390590, 289258448, 889304859, 2742205395, 8478653638, 26280715255, 81648362339, 254204771596, 793011895972, 2478427376313, 7759251412310
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OFFSET
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1,4
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COMMENTS
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Compare g.f. to: G(x) = x + G( G(x)^2/(1 + G(x) + G(x)^2) ) when G(x) = x/(1-x).
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LINKS
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EXAMPLE
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G.f.: A(x) = x + x^2 + x^3 + 2*x^4 + 5*x^5 + 12*x^6 + 30*x^7 + 80*x^8 +...
Related expansions:
A(x)^2 = x^2 + 2*x^3 + 3*x^4 + 6*x^5 + 15*x^6 + 38*x^7 + 98*x^8 +...
A(x)^2/(1 + A(x)) = x^2 + x^3 + x^4 + 3*x^5 + 8*x^6 + 19*x^7 + 49*x^8 +...
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PROG
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(PARI) {a(n)=local(A=x+x^2); for(i=1, n, A=x+subst(A, x, A^2/(1+A+x*O(x^n)))); polcoeff(A, n)}
for(n=1, 40, print1(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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