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Search: id:A139715
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| A139715 |
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G.f. A(x) satisfies: A(x) = G(G(x)) where G(x) = x - A(x)^2 = g.f. of A139702. |
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+0
1
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| 1, -2, 10, -69, 568, -5250, 52792, -566830, 6420640, -76095972, 938077528, -11975951312, 157808048792, -2140767942096, 29835756120952, -426490803168368, 6244476409802008, -93541594534237356, 1432261132629484052, -22397290780155132728
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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Series_Reversion(A(x)) = F(F(x)) = F(x) + x^2 where F(x) = g.f. of A138740.
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EXAMPLE
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A(x) = x - 2*x^2 + 10*x^3 - 69*x^4 + 568*x^5 - 5250*x^6 + 52792*x^7 -+...
Let G(x) = x - A(x)^2 = g.f. of A139702:
G(x) = x - x^2 + 4*x^3 - 24*x^4 + 178*x^5 - 1512*x^6 + 14152*x^7 -+...
then A(x) = G(G(x)).
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PROGRAM
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(PARI) {a(n)=local(A=x); if(n<1, 0, for(i=1, n, A=serreverse(x + (A+x*O(x^n))^2)); polcoeff(subst(A, x, A+x*O(x^n)), n))}
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CROSSREFS
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Cf. A139702, A138740.
Sequence in context: A104098 A056755 A123617 this_sequence A051575 A121201 A166076
Adjacent sequences: A139712 A139713 A139714 this_sequence A139716 A139717 A139718
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KEYWORD
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sign
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Apr 30 2008
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