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A213095
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G.f. satisfies: A(x) = 1 + x/A(-x*A(x)^5)^2.
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23
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1, 1, 2, 9, 40, 242, 1528, 10664, 76956, 575245, 4395910, 34131621, 268146598, 2122399923, 16884293154, 134689290877, 1075641369024, 8588548510081, 68496446989330, 545303352881863, 4331918361300882, 34337864000400360, 271657823631727330, 2146133623039711577
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OFFSET
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0,3
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COMMENTS
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Compare definition of g.f. to:
(1) B(x) = 1 + x/B(-x*B(x)) when B(x) = 1/(1-x).
(2) C(x) = 1 + x/C(-x*C(x)^3)^2 when C(x) = 1 + x*C(x)^2 is the g.f. of the Catalan numbers (A000108).
(3) D(x) = 1 + x/D(-x*D(x)^5)^3 when D(x) = 1 + x*D(x)^3 is the g.f. of the ternary tree numbers (A001764).
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LINKS
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EXAMPLE
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G.f.: A(x) = 1 + x + 2*x^2 + 7*x^3 + 26*x^4 + 123*x^5 + 622*x^6 + 3490*x^7 +...
Related expansions:
A(x)^5 = 1 + 5*x + 20*x^2 + 95*x^3 + 485*x^4 + 2801*x^5 + 17560*x^6 +...
A(-x*A(x)^5)^2 = 1 - 2*x - 5*x^2 - 12*x^3 - 93*x^4 - 550*x^5 - 3981*x^6 -...
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MATHEMATICA
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m = 23; A[_] = 1; Do[A[x_] = 1 + x/A[-x A[x]^5 + O[x]^m]^2 // Normal, {m}];
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PROG
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(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=1, n, A=1+x/subst(A^2, x, -x*subst(A^5, x, x+x*O(x^n))) ); polcoeff(A, n)}
for(n=0, 30, print1(a(n), ", "))
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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