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Search: id:A052974
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| A052974 |
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A simple regular expression. |
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+0
1
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| 1, 0, 1, 3, 5, 14, 34, 81, 200, 487, 1187, 2899, 7072, 17256, 42109, 102748, 250717, 611779, 1492805, 3642610, 8888370, 21688597, 52922564, 129136875, 315108171, 768898587, 1876197092, 4578127192, 11171133721, 27258794552, 66514455833
(list; graph; listen)
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OFFSET
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0,4
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1046
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FORMULA
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G.f.: -(-1+2*x)/(1-2*x-x^3+2*x^4-x^2)
Recurrence: {a(1)=0, a(0)=1, a(2)=1, a(3)=3, 2*a(n)-a(n+1)-a(n+2)-2*a(n+3)+a(n+4)}
Sum(1/4999*(-159+1343*_alpha-450*_alpha^2+136*_alpha^3)*_alpha^(-1-n), _alpha=RootOf(1-2*_Z-_Z^3+2*_Z^4-_Z^2))
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MAPLE
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spec := [S, {S=Sequence(Prod(Union(Sequence(Union(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: A104208 A026777 A007136 this_sequence A006395 A078718 A081393
Adjacent sequences: A052971 A052972 A052973 this_sequence A052975 A052976 A052977
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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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