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A052867
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E.g.f.: log(-(-1+x)^2/(-1+2*x)).
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0
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0, 0, 2, 12, 84, 720, 7440, 90720, 1280160, 20563200, 370863360, 7424524800, 163419379200, 3923023104000, 102011054745600, 2856483889459200, 85697132032512000, 2742350070620160000, 93240613775941632000
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OFFSET
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0,3
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COMMENTS
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Previous name was: A simple grammar.
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LINKS
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FORMULA
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D-finite with Recurrence: {a(1)=0, a(2)=2, (2*n^2+2*n)*a(n)-3*(n+1)*a(n+1)+a(n+2)}.
a(n) = -2*GAMMA(n+1)+2^(n+1)*GAMMA(n+1).
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MAPLE
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spec := [S, {B=Sequence(Z, 1 <= card), C=Prod(B, B), S= Cycle(C)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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MATHEMATICA
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Range[0, 19]! CoefficientList[Series[Log[-(-1 + x)^2/(-1 + 2 x)], {x, 0, 19}], x] (* Vincenzo Librandi, Jul 09 2015 *)
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CROSSREFS
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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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