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Search: id:A052997
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| A052997 |
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A simple regular expression. |
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+0
1
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| 1, 3, 7, 14, 29, 58, 117, 234, 469, 938, 1877, 3754, 7509, 15018, 30037, 60074, 120149, 240298, 480597, 961194, 1922389, 3844778, 7689557, 15379114, 30758229, 61516458, 123032917, 246065834, 492131669, 984263338, 1968526677
(list; graph; listen)
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OFFSET
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0,2
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1075
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FORMULA
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G.f.: -(-x+x^3-1)/(-1+x^2)/(-1+2*x)
Recurrence: {a(0)=1, -2*a(n)-a(n+1)+a(n+2)-1, a(1)= 3, a(2)=7, a(3)=14}
11/6*2^n+Sum(-1/6*(2+_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+_Z^2))
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MAPLE
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spec := [S, {S=Prod(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
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Sequence in context: A151754 A157672 A125899 this_sequence A074988 A066225 A139817
Adjacent sequences: A052994 A052995 A052996 this_sequence A052998 A052999 A053000
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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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