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A052833
Expansion of e.g.f.: (log(2-exp(x)))^2.
1
0, 0, 2, 12, 72, 500, 4080, 38668, 419160, 5124708, 69831360, 1049972924, 17273719848, 308714206996, 5956836347280, 123437573728620, 2734197673727736, 64473939310567364, 1612626113517932640, 42645398700110627356, 1188880256538133537224, 34849264499702702749812
OFFSET
0,3
COMMENTS
Previous name was: A simple grammar.
LINKS
FORMULA
E.g.f.: log(-1/(-2+exp(x)))^2.
a(n) ~ (n-1)! * 2*(log(n) + gamma - log(2) - log(log(2)))/log(2)^n, where gamma is Euler-Mascheroni constant (A001620). - Vaclav Kotesovec, Sep 30 2013
MAPLE
spec := [S, {B=Set(Z, 1 <= card), C=Cycle(B), S=Prod(C, C)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
MATHEMATICA
CoefficientList[Series[Log[2-E^x]^2, {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Sep 30 2013 *)
PROG
(PARI) x='x+O('x^30); concat([0, 0], Vec(serlaplace((log(2-exp(x)))^2))) \\ G. C. Greubel, Sep 05 2018
CROSSREFS
Sequence in context: A181966 A052556 A371039 * A277490 A296975 A144086
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
EXTENSIONS
New name, using e.g.f., by Vaclav Kotesovec, Sep 30 2013
More terms from Alois P. Heinz, Mar 16 2016
STATUS
approved