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Search: id:A052607
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| A052607 |
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A simple regular expression in a labeled universe. |
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+0
1
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| 1, 0, 2, 0, 24, 120, 720, 10080, 80640, 1088640, 14515200, 199584000, 3353011200, 56043187200, 1046139494400, 20922789888000, 439378587648000, 9959247986688000, 236887827111936000, 5960609920032768000
(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 552
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FORMULA
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E.g.f.: (-1+x^3)/(-1+x^2+x^3)
Recurrence: {a(1)=0, a(0)=1, a(3)=0, a(2)=2, (-11*n-6-n^3-6*n^2)*a(n)+(-n^2-5*n-6)*a(n+1)+a(n+3)}
Sum(-1/23*(6*_alpha^2+2*_alpha-9)*_alpha^(-1-n), _alpha=RootOf(_Z^3+_Z^2-1))*n!
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MAPLE
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spec := [S, {S=Sequence(Prod(Z, Z, Sequence(Prod(Z, Z, Z))))}, labeled]: [seq(combstruct[count](spec, size=n), n=0..20)];
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CROSSREFS
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Sequence in context: A008842 A130915 A127067 this_sequence A052602 A012588 A012290
Adjacent sequences: A052604 A052605 A052606 this_sequence A052608 A052609 A052610
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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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