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Search: id:A120575
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| A120575 |
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G.f. satisfies: A(x) = x + 2*x*A(x) + x*A(A(x)). |
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+0
2
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| 1, 3, 12, 66, 471, 4044, 39711, 433128, 5153655, 66087525, 905350476, 13162855629, 202073897730, 3262403607924, 55206822277551, 976489740673734, 18010559992528317, 345674349652856367, 6891047565127733874
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OFFSET
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1,2
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EXAMPLE
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A(x) = x + 3*x^2 + 12*x^3 + 66*x^4 + 471*x^5 + 4044*x^6 + 39711*x^7 +...
A(A(x)) = x + 6*x^2 + 42*x^3 + 339*x^4 + 3102*x^5 + 31623*x^6 +...
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PROGRAM
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(PARI) {a(n)=local(F=x+x*O(x^n), G=F); for(i=1, n, F=x+2*x*F+x*subst(F, x, F)); polcoeff(F, n)}
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CROSSREFS
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Cf. A120574.
Sequence in context: A007871 A058790 A080599 this_sequence A123227 A009362 A107713
Adjacent sequences: A120572 A120573 A120574 this_sequence A120576 A120577 A120578
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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), Jun 15 2006
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