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A106184
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Expansion of 1/sqrt(1-4x-8x^2+32x^3).
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0
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1, 2, 10, 28, 118, 380, 1508, 5240, 20326, 73836, 284396, 1061128, 4085820, 15500120, 59820040, 229366768, 887943046, 3428967500, 13315684764, 51678099304, 201246353492, 783890932488, 3060144292600, 11953056489104
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| In general, a(n)=sum{k=0..floor(n/2), C(2k,k)C(2(n-2k),n-2k)*r^k} has g.f. 1/sqrt(1-4x-4r*x^2+16r*x^3).
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FORMULA
| a(n)=sum{k=0..floor(n/2), C(2k, k)C(2(n-2k), n-2k)*2^k}.
Conjecture: n*a(n)+2(1-2n)*a(n-1)+8*(1-n)*a(n-2)+16*(2n-3)*a(n-3)=0. - R. J. Mathar, Dec 08 2011
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MATHEMATICA
| CoefficientList[Series[1/Sqrt[1-4x-8x^2+32x^3], {x, 0, 30}], x] (* From Harvey P. Dale, Sep 15 2011 *)
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CROSSREFS
| Sequence in context: A000900 A124023 A127921 * A076438 A203551 A192976
Adjacent sequences: A106181 A106182 A106183 * A106185 A106186 A106187
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Apr 24 2005
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