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Search: id:A052930
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| A052930 |
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A simple regular expression. |
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+0
1
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| 1, 0, 2, 4, 6, 18, 34, 74, 166, 346, 758, 1634, 3510, 7602, 16374, 35330, 76262, 164466, 354902, 765698, 1651910, 3564178, 7689590, 16590370, 35794086, 77225650, 166615382, 359474114, 775568006, 1673295698, 3610149174
(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 916
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FORMULA
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G.f.: -(-1+x)/(1-x-2*x^3+2*x^4-2*x^2)
Recurrence: {a(1)=0, a(0)=1, a(3)=4, a(2)=2, 2*a(n)-2*a(n+1)-2*a(n+2)-a(n+3)+a(n+4)}
Sum(-1/1651*(-101-469*_alpha+236*_alpha^2+30*_alpha^3)*_alpha^(-1-n), _alpha=RootOf(1-_Z-2*_Z^3+2*_Z^4-2*_Z^2))
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MAPLE
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spec := [S, {S=Sequence(Prod(Union(Sequence(Z), Z), Union(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: A075229 A073664 A088174 this_sequence A098853 A085146 A066894
Adjacent sequences: A052927 A052928 A052929 this_sequence A052931 A052932 A052933
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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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