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Search: id:A052652
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| A052652 |
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A simple regular expression in a labeled universe. |
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+0
1
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| 0, 0, 0, 0, 24, 240, 2880, 40320, 645120, 11612160, 232243200, 5109350400, 122624409600, 3188234649600, 89270570188800, 2678117105664000, 85699747381248000, 2913791410962432000, 104896490794647552000
(list; graph; listen)
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OFFSET
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0,5
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 599
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FORMULA
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E.g.f.: -x^4/(-1+2*x)
Recurrence: {a(1)=0, a(0)=0, a(2)=0, a(3)=0, (-2*n-2)*a(n)+a(n+1), a(4)=24}
1/16*2^n*n!
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MAPLE
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spec := [S, {S=Prod(Z, Z, Z, Z, Sequence(Union(Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A052724 A000536 A151720 this_sequence A052732 A086603 A000594
Adjacent sequences: A052649 A052650 A052651 this_sequence A052653 A052654 A052655
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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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