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Search: id:A052601
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| A052601 |
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A simple regular expression in a labeled universe. |
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+0
1
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| 1, 0, 0, 12, 48, 240, 4320, 50400, 564480, 9434880, 166924800, 2953843200, 60354201600, 1357490534400, 31907254579200, 808142759424000, 22052620541952000, 635257746579456000, 19347973338710016000
(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 546
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FORMULA
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E.g.f.: (-1+x)/(-1+x+2*x^3)
Recurrence: {a(1)=0, a(0)=1, a(2)=0, (-12*n^2-22*n-12-2*n^3)*a(n)+(-n-3)*a(n+2)+a(n+3)}
Sum(-1/29*(1+3*_alpha^2-10*_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+_Z+2*_Z^3))*n!
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MAPLE
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spec := [S, {S=Sequence(Prod(Z, Z, Sequence(Z), Union(Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Adjacent sequences: A052598 A052599 A052600 this_sequence A052602 A052603 A052604
Sequence in context: A117027 A007200 A061148 this_sequence A003498 A002899 A077612
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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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