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Search: id:A052926
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| A052926 |
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A simple regular expression. |
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+0
1
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| 1, 1, 5, 18, 74, 299, 1216, 4941, 20083, 81625, 331760, 1348416, 5480549, 22275332, 90536629, 367980201, 1495631437, 6078896062, 24707275082, 100421102079, 408154995212, 1658919257681, 6742568719699, 27404729150841
(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 912
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FORMULA
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G.f.: -(-1+3*x)/(1-4*x-x^2+3*x^3)
Recurrence: {a(1)=1, a(0)=1, a(2)=5, 3*a(n)-a(n+1)-4*a(n+2)+a(n+3)}
Sum(-1/761*(17-278*_alpha+15*_alpha^2)*_alpha^(-1-n), _alpha=RootOf(1-4*_Z-_Z^2+3*_Z^3))
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MAPLE
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spec := [S, {S=Sequence(Prod(Z, Union(Z, Sequence(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: A109438 A134764 A034551 this_sequence A027134 A017960 A082034
Adjacent sequences: A052923 A052924 A052925 this_sequence A052927 A052928 A052929
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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 08 2000
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