OFFSET
0,3
COMMENTS
Previous name was: A simple grammar.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..313
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 746
FORMULA
E.g.f.: -(1/5)*LambertW(-5*x).
For n > 0, a(n) = (5*n)^(n-1). - Vaclav Kotesovec, Sep 30 2013
a(n) = [x^n] x/(1 - 5*n*x). - Ilya Gutkovskiy, Oct 12 2017
MAPLE
spec := [S, {B=Set(S), S=Prod(Z, B, B, B, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
MATHEMATICA
CoefficientList[Series[-1/5*LambertW[-5*x], {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Sep 30 2013 *)
PROG
(PARI) x='x+O('x^50); concat([0], Vec(serlaplace(- lambertw(-5*x)/5))) \\ G. C. Greubel, Nov 08 2017
CROSSREFS
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
STATUS
approved