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A052935
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Expansion of (2-2x-x^3)/((1-2x)(1-x^3)).
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0
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2, 2, 4, 9, 16, 32, 65, 128, 256, 513, 1024, 2048, 4097, 8192, 16384, 32769, 65536, 131072, 262145, 524288, 1048576, 2097153, 4194304, 8388608, 16777217, 33554432, 67108864, 134217729, 268435456, 536870912, 1073741825, 2147483648
(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 923
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FORMULA
| G.f.: -(-2+2*x+x^3)/(-1+x^3)/(-1+2*x)
Recurrence: {a(2)=4, a(1)=2, a(0)=2, a(3)=9, -2*a(n)-a(n+1)-a(n+2)+a(n+3)+1=0}
2^n+Sum(1/3*_alpha^(-n), _alpha=RootOf(-1+_Z^3))
a(n) = 2*A033138(n+1)-2*A033138(n)-A033138(n-2). - R. J. Mathar, Nov 28 2011
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MAPLE
| spec := [S, {S=Union(Sequence(Prod(Z, Z, Z)), Sequence(Union(Z, Z)))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A054230 A054232 A100048 * A166022 A052925 A006182
Adjacent sequences: A052932 A052933 A052934 * A052936 A052937 A052938
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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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