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Search: id:A138913
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| A138913 |
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G.f. A(x) satisfies: 4*A(x) = A(A(A(x))) + 3*x + x^2 with A(0)=0. |
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+0
4
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| 1, 1, 6, 99, 2362, 70484, 2463460, 97309959, 4251047468, 202470323828, 10409697289888, 573563068625768, 33682595044746416, 2099111839596600644, 138339363094940014088, 9612941947359915802978, 702527738704990333954432
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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A(A(A(x))) is the 3-rd self-composition of the g.f. A(x).
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EXAMPLE
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G.f.: A(x) = x + x^2 + 6*x^3 + 99*x^4 + 2362*x^5 + 70484*x^6 +...
A(A(x)) = x + 2*x^2 + 14*x^3 + 229*x^4 + 5456*x^5 + 162710*x^6 +...
A(A(A(x))) = x + 3*x^2 + 24*x^3 + 396*x^4 + 9448*x^5 + 281936*x^6 +...
so that 4*A(x) = A(A(A(x))) + 3*x + x^2.
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PROGRAM
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(PARI) {a(n)=local(A=x+x^2); if(n<1, 0, for(i=3, n+1, A=A+polcoeff(subst(A, x, subst(A, x, A+x*O(x^i))), i)*x^i); polcoeff(A, n))}
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CROSSREFS
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Cf. A138739, A138914, A138915, A138916.
Sequence in context: A066319 A111826 A064753 this_sequence A127636 A131311 A098721
Adjacent sequences: A138910 A138911 A138912 this_sequence A138914 A138915 A138916
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Apr 03 2008
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