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Search: id:A052969
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| A052969 |
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A simple regular expression. |
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+0
1
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| 1, 0, 2, 2, 5, 9, 17, 33, 62, 119, 226, 431, 821, 1564, 2980, 5677, 10816, 20606, 39258, 74793, 142493, 271473, 517201, 985354, 1877263, 3576498, 6813823, 12981465, 24731848, 47118280, 89768153, 171023248, 325827706, 620755922, 1182643181
(list; graph; listen)
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OFFSET
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0,3
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1041
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FORMULA
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G.f.: -(-1+x)/(1-2*x^2+x^4-x)
Recurrence: {a(1)=0, a(0)=1, a(2)=2, a(3)=2, a(n)-2*a(n+2)-a(n+3)+a(n+4)}
Sum(1/283*(29*_alpha+28*_alpha^3-76*_alpha^2+55)*_alpha^(-1-n), _alpha=RootOf(1-2*_Z^2+_Z^4-_Z))
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MAPLE
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spec := [S, {S=Sequence(Prod(Union(Prod(Union(Sequence(Z), Z), Z), Z), Z))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A096569 A076607 A054229 this_sequence A002990 A060405 A003228
Adjacent sequences: A052966 A052967 A052968 this_sequence A052970 A052971 A052972
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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 05 2000
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