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Search: id:A052996
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| A052996 |
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G.f.: (1+x^2-x^3)/((1-x)(1-2*x)). |
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+0
2
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| 1, 3, 8, 17, 35, 71, 143, 287, 575, 1151, 2303, 4607, 9215, 18431, 36863, 73727, 147455, 294911, 589823, 1179647, 2359295, 4718591, 9437183, 18874367, 37748735, 75497471, 150994943, 301989887, 603979775, 1207959551, 2415919103
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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A simple regular expression.
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1074
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FORMULA
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Recurrence: {a(0)=1, -2*a(n)+a(n+1)-1, a(3)=17, a(2)=8, a(1)=3}
-1+9/4*2^n
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MAPLE
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spec := [S, {S=Prod(Union(Prod(Z, Z), Sequence(Z)), Sequence(Union(Z, Z)))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A002626 A029859 A131253 this_sequence A112523 A106691 A140176
Adjacent sequences: A052993 A052994 A052995 this_sequence A052997 A052998 A052999
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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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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jun 06 2000
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