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A052904
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Expansion of (1-x)/(1-2x-4x^2+4x^3).
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1
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1, 1, 6, 12, 44, 112, 352, 976, 2912, 8320, 24384, 70400, 205056, 594176, 1726976, 5010432, 14552064, 42237952, 122642432, 356028416, 1033674752, 3000893440, 8712372224, 25293619200, 73433153536, 213191294976, 618940727296
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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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G.f.: -(-1+x)/(1-2*x-4*x^2+4*x^3)
Recurrence: {a(1)=1, a(0)=1, a(2)=6, 4*a(n)-4*a(n+1)-2*a(n+2)+a(n+3)=0}
Sum(-1/37*(-4-14*_alpha+13*_alpha^2)*_alpha^(-1-n), _alpha=RootOf(1-2*_Z-4*_Z^2+4*_Z^3))
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MAPLE
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spec := [S, {S=Sequence(Prod(Z, Union(Sequence(Z), Z, Z, Z, Z)))}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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MATHEMATICA
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CoefficientList[Series[(1-x)/(1-2x-4x^2+4x^3), {x, 0, 30}], x] (* or *) LinearRecurrence[{2, 4, -4}, {1, 1, 6}, 30] (* Harvey P. Dale, Jan 17 2013 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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EXTENSIONS
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STATUS
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approved
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