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A052522
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Number of labeled mobiles with cycles of length at least 3.
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0
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0, 1, 0, 2, 6, 64, 540, 6908, 93744, 1542616, 28057800, 576840032, 13029824016, 323152349584, 8698499671680, 252998272144928, 7900336700736864, 263731233726459136, 9370598887948893120, 353114271843930110912
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 90
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FORMULA
| E.g.f.: (exp(RootOf(2*_Z*exp(_Z)^2-5*exp(_Z)^2+6*exp(_Z)+2*x*exp(_Z)^2-1))-1)/exp(RootOf(2*_Z*exp(_Z)^2-5*exp(_Z)^2+6*exp(_Z)+2*x*exp(_Z)^2-1))
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MAPLE
| spec := [S, {S=Union(B, Z), B=Cycle(S, 3 <= card)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A030170 A082640 A139695 * A193609 A061999 A066756
Adjacent sequences: A052519 A052520 A052521 * A052523 A052524 A052525
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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