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Search: id:A052932
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| A052932 |
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A simple regular expression. |
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+0
1
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| 1, 1, 2, 4, 9, 18, 37, 76, 157, 323, 665, 1369, 2819, 5804, 11950, 24604, 50658, 104301, 214748, 442150, 910354, 1874351, 3859149, 7945700, 16359604, 33683205, 69351208, 142788967, 293991838, 605307277, 1246282557, 2566002873
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Equals INVERT transform of (1, 1, 1, 2, 1, 1, 1, 1,...) [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Apr 27 2009]
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 918
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FORMULA
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G.f.: -(-1+x)/(1-2*x+x^5-x^4)
Recurrence: {a(1)=1, a(0)=1, a(3)=4, a(2)=2, a(4)=9, a(n)-a(n+1)-2*a(n+4)+a(n+5)}
Sum(-1/11243*(-1630*_alpha-319*_alpha^2-428*_alpha^3+1268*_alpha^4-1807)*_alpha^(-1-n), _alpha=RootOf(1-2*_Z+_Z^5-_Z^4))
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MAPLE
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spec := [S, {S=Sequence(Prod(Union(Sequence(Z), Prod(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: A081253 A118255 A019299 this_sequence A018097 A079580 A018000
Adjacent sequences: A052929 A052930 A052931 this_sequence A052933 A052934 A052935
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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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