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Search: id:A052917
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| A052917 |
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A simple regular expression. |
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+0
1
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| 1, 3, 9, 27, 82, 249, 756, 2295, 6967, 21150, 64206, 194913, 591706, 1796268, 5453010, 16553943, 50253535, 152556873, 463123629, 1405924830, 4268028025, 12956640948, 39333046473, 119405064249, 362483220772, 1100406303264
(list; graph; listen)
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OFFSET
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0,2
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 900
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FORMULA
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G.f.: -1/(-1+3*x+x^4)
Recurrence: {a(0)=1, a(1)=3, a(2)=9, a(n)+3*a(n+3)-a(n+4), a(3)=27}
Sum(1/2443*(729+324*_alpha^3+144*_alpha^2+64*_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+3*_Z+_Z^4))
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MAPLE
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spec := [S, {S=Sequence(Union(Z, Z, 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: A067500 A078226 A083591 this_sequence A099786 A131428 A099787
Adjacent sequences: A052914 A052915 A052916 this_sequence A052918 A052919 A052920
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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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