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A055142
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Expansion of e.g.f.: exp(x)*sqrt(1-2x).
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5
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1, 0, -2, -8, -36, -224, -1880, -19872, -251888, -3712256, -62286624, -1171487360, -24402416192, -557542291968, -13861636770176, -372514645389824, -10759590258589440, -332386419622387712
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OFFSET
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0,3
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LINKS
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FORMULA
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D-finite with recurrence: a(n) +2*(-n+1)*a(n-1) +2*(n-1)*a(n-2)=0. - R. J. Mathar, Jan 22 2020
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MATHEMATICA
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CoefficientList[Series[E^x*Sqrt[1-2*x], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Mar 29 2014 *)
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PROG
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(Sage)
@CachedFunction
def h(n):
return (-1)^n*2*(n-2)*abs(h(n-1)+h(n-2)) if n>1 else 1
return -(-1)^(n+1)*h(n+1)
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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