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Search: id:A141121
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| A141121 |
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G.f. A(x) satisfies: A(A(A(A(A(A(x)))))) = x + 36*x^2. |
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+0
4
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| 1, 6, -180, 8640, -498960, 31434480, -2055943296, 135216506304, -8720972739072, 538646016002688, -31024094144060160, 1609593032459782656, -71392972690228672512, 2461961564459510280192, -51302015299696881770496, -415041229811424576835584
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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G.f.: A(x) = x + 6*x^2 - 180*x^3 + 8640*x^4 - 498960*x^5 +...
A(A(x)) = x + 12*x^2 - 288*x^3 + 12096*x^4 - 622080*x^5 +...
A(A(A(x))) = x + 18*x^2 - 324*x^3 + 11664*x^4 - 524880*x^5 +...
A(A(A(A(x)))) = x + 24*x^2 - 288*x^3 + 8640*x^4 - 331776*x^5 +...
A(A(A(A(A(x))))) = x + 30*x^2 - 180*x^3 + 4320*x^4 - 136080*x^5 +...
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PROGRAM
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(PARI) {a(n, m=6)=local(F=x+m*x^2+x*O(x^n), G); if(n<1, 0, for(k=3, n, G=F+x*O(x^k); for(i=1, m-1, G=subst(F, x, G)); F=F+((-polcoeff(G, k))/m)*x^k); return(polcoeff(F, n, x)))}
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CROSSREFS
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Cf. A027436, A141119, A141119, A141120.
Adjacent sequences: A141118 A141119 A141120 this_sequence A141122 A141123 A141124
Sequence in context: A062240 A046989 A135395 this_sequence A051357 A064120 A041429
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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), Jun 05 2008
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