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Search: id:A120953
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| A120953 |
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G.f. A(x) equals series_reversion(x/F(x))/x where F(x) is the g.f. of A120952; a(2*n+1) = 0 for n>=1. |
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3
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| 1, 1, 3, 0, -65, 0, 4998, 0, -691749, 0, 142819050, 0, -40447525482, 0, 14988562779660, 0, -7042958511356013, 0, 4098696561237950274, 0, -2898331335691958097918, 0, 2450632554538246780555476, 0, -2443617360583149618790999650, 0
(list; graph; listen)
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OFFSET
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0,3
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FORMULA
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G.f. satisfies: A(x) = F(x*A(x)) and F(x) = A(x/F(x)) where F(x) = g.f. of A120952.
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EXAMPLE
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A(x) = 1 + x + 3*x^2 - 65*x^4 + 4998*x^6 - 691749*x^8 +-...
The g.f. of A120952 is:
F(x) = 1 + x + 2*x^2 - 7*x^3 - 58*x^4 + 369*x^5 + 4572*x^6 --++...
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PROGRAM
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(PARI) {a(n)=local(A=[1, 1]); for(i=1, n, if(#A%2==1, A=concat(A, t); A[ #A]=-subst(Vec(serreverse(x/Ser(A)))[ #A], t, 0)); if(#A%2==0, A=concat(A, t); A[ #A]=subst(Vec(serreverse(x*Ser(A)))[ #A], t, 0))); Vec(serreverse(x/Ser(A)))[n+1]}
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CROSSREFS
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Cf. A120952, A120954.
Adjacent sequences: A120950 A120951 A120952 this_sequence A120954 A120955 A120956
Sequence in context: A009786 A012738 A012759 this_sequence A009784 A013245 A013238
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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), Jul 19 2006
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