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A052803
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A simple grammar.
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2
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1, 1, 5, 44, 566, 9674, 207166, 5343456, 161405016, 5591409720, 218592034584, 9521490534720, 457329182411856, 24014921905589328, 1368772939062117936, 84161443919543331840, 5553011951023694408064, 391360838810043628416384
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,3
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LINKS
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Table of n, a(n) for n=0..17.
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 762
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FORMULA
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E.g.f.: (1/2)/ln(-1/(-1+x))*(1-(1-4*ln(-1/(-1+x)))^(1/2))
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MAPLE
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spec := [S, {C=Cycle(Z), S=Sequence(B), B=Prod(C, S)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A215648 A195242 A106273 * A201923 A222059 A048940
Adjacent sequences: A052800 A052801 A052802 * A052804 A052805 A052806
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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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STATUS
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approved
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