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A052867 E.g.f.: log(-(-1+x)^2/(-1+2*x)). 0
0, 0, 2, 12, 84, 720, 7440, 90720, 1280160, 20563200, 370863360, 7424524800, 163419379200, 3923023104000, 102011054745600, 2856483889459200, 85697132032512000, 2742350070620160000, 93240613775941632000 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
Previous name was: A simple grammar.
LINKS
FORMULA
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).
a(n) = 2*A052589(n-1). - R. J. Mathar, Jun 03 2022
MAPLE
spec := [S, {B=Sequence(Z, 1 <= card), C=Prod(B, B), S= Cycle(C)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
MATHEMATICA
Range[0, 19]! CoefficientList[Series[Log[-(-1 + x)^2/(-1 + 2 x)], {x, 0, 19}], x] (* Vincenzo Librandi, Jul 09 2015 *)
CROSSREFS
Sequence in context: A362245 A362237 A052887 * A226238 A179495 A348765
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
STATUS
approved

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Last modified March 3 08:25 EST 2024. Contains 370499 sequences. (Running on oeis4.)