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A049140
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Revert transform of 1 - x - x^3.
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15
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1, 1, 2, 6, 20, 70, 256, 969, 3762, 14894, 59904, 244088, 1005452, 4180096, 17516936, 73913705, 313774854, 1339162028, 5742691704, 24731501410, 106919054880, 463844340060, 2018673093000, 8810852089650, 38558866555248
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OFFSET
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1,3
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COMMENTS
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Series reversion of x-x^2-x^4. - Joerg Arndt, May 24 2011
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LINKS
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FORMULA
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a(n) = sum(j=0..(n-1)/2, binomial(n-2*j-1,j)*binomial(2*n-2*j-2,n-1))/n. - Vladimir Kruchinin, May 24 2011
D-finite with recurrence 31*n*(n-1)*(n-2)*(140*n-383)*a(n) -8*(n-1)*(n-2)*(2800*n^2 -11860*n+11583)*a(n-1) +4*(n-2)*(4480*n^3-30176*n^2+66916*n-48753)*a(n-2) -8*(4*n-11)*(4*n-13)*(140*n-243)*(2*n-5)*a(n-3) = 0. - R. J. Mathar, Sep 29 2012
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MATHEMATICA
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PROG
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(Maxima)
a(n):=sum(binomial(n-2*j-1, j)*binomial(2*n-2*j-2, n-1), j, 0, (n-1)/2)/n; /* Vladimir Kruchinin, May 24 2011 */
(PARI) Vec(serreverse(x*(1-x-x^3+O(x^66)))) /* Joerg Arndt, May 24 2011 */
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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