OFFSET
0,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..418
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 787
FORMULA
E.g.f.: log(-1/(-1+log(-1/(-1+x))))^2.
E.g.f.: (log(1+log(1-x)))^2. - Vaclav Kotesovec, Oct 01 2013
a(n) ~ (n-1)! * 2*(exp(1)/(exp(1)-1))^n * (log(n) + gamma - log(exp(1)-1)), where gamma is Euler-Mascheroni constant (A001620). - Vaclav Kotesovec, Oct 01 2013
MAPLE
spec := [S, {B=Cycle(Z), C=Cycle(B), S=Prod(C, C)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
MATHEMATICA
CoefficientList[Series[(Log[1+Log[1-x]])^2, {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Oct 01 2013 *)
PROG
(PARI) x='x+O('x^30); concat([0, 0], Vec(serlaplace((log(1+log(1-x)))^2))) \\ G. C. Greubel, Aug 30 2018
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
EXTENSIONS
More terms from Alois P. Heinz, Mar 16 2016
STATUS
approved