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Search: id:A139085
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| A139085 |
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G.f. satisfies: 2*A(x) = 3*x + x^2 - Series_Reversion( A(x) ). |
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+0
2
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| 1, 1, -2, 15, -158, 2058, -31148, 529209, -9882430, 200035242, -4346788764, 100697241762, -2473869382964, 64191822293220, -1753530264442280, 50293662225989739, -1511101241900117982, 47467602491174747046
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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a(n) = (1/2)*(-1)^n*A139086(n) for n>2 with a(1)=a(2)=1.
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EXAMPLE
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G.f.: A(x) = x + x^2 - 2*x^3 + 15*x^4 - 158*x^5 + 2058*x^6 -+...
Series_Reversion(A(x)) = x - x^2 + 4*x^3 - 30*x^4 + 316*x^5 -+...
which equals -G(-x) where G(x) = g.f. of A139086.
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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(serreverse(A+x*O(x^i)), i)*x^i); polcoeff(A, n))}
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CROSSREFS
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Cf. A139086.
Sequence in context: A060226 A002103 A124548 this_sequence A140809 A153852 A117667
Adjacent sequences: A139082 A139083 A139084 this_sequence A139086 A139087 A139088
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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 08 2008
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