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Search: id:A052593
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| A052593 |
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A simple regular expression in a labeled universe. |
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+0
2
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| 1, 1, 2, 6, 48, 360, 2880, 25200, 282240, 3628800, 50803200, 758419200, 12454041600, 224172748800, 4358914560000, 90229531392000, 1987665039360000, 46595053080576000, 1158829640736768000
(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 538
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FORMULA
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E.g.f.: -1/(-1+x^4+x)
Recurrence: {a(1)=1, a(0)=1, a(3)=6, a(2)=2, (-n^4-35*n^2-50*n-24-10*n^3)*a(n)+(-n-4)*a(n+3)+a(n+4)}
Sum(1/283*(27+36*_alpha^3+48*_alpha^2+64*_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+_Z^4+_Z))*n!
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MAPLE
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spec := [S, {S=Sequence(Union(Z, Prod(Z, Z, Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
a:= n-> n! * (Matrix([[1, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 1], [1, 0, 0, 0]])^n)[1, 1]: seq (a(n), n=0..20); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Jun 01 2009]
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CROSSREFS
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Row sums of A145142. [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Jun 01 2009]
Sequence in context: A052688 A052657 A092143 this_sequence A052586 A052554 A052743
Adjacent sequences: A052590 A052591 A052592 this_sequence A052594 A052595 A052596
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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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