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A052925
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Expansion of (2-6x+4x^2-x^3)/((1-x)(1-3x+x^2)).
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1
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2, 2, 4, 9, 22, 56, 145, 378, 988, 2585, 6766, 17712, 46369, 121394, 317812, 832041, 2178310, 5702888, 14930353, 39088170, 102334156, 267914297, 701408734, 1836311904, 4807526977, 12586269026, 32951280100, 86267571273
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 910
Index to sequences with linear recurrences with constant coefficients, signature (4,-4,1).
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FORMULA
| G.f.: (-2+6*x-4*x^2+x^3)/(-1+x)/(1-3*x+x^2)
Recurrence: {a(2)=4, a(1)=2, a(0)=2, a(3)=9, -a(n)+3*a(n+1)-a(n+2)-1}
1+Sum(-1/5*(3*_alpha-2)*_alpha^(-1-n), _alpha=RootOf(_Z^2-3*_Z+1))
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MAPLE
| spec := [S, {S=Union(Sequence(Z), Sequence(Prod(Sequence(Z), Sequence(Z), Z)))}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Apart from first term, same as A055588.
Sequence in context: A100048 A052935 A166022 * A006182 A121623 A202802
Adjacent sequences: A052922 A052923 A052924 * A052926 A052927 A052928
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jun 05 2000
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