OFFSET
0,3
COMMENTS
Previous name was: A simple grammar.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..450
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 831
FORMULA
E.g.f.: log(-1/(-1+x))*exp(x) - log(-1/(-1+x)).
Recurrence: {a(1)=0, a(3)=6, a(2)=2, (-n^3-2*n-3*n^2)*a(n)+(19*n+11*n^2+2*n^3+10)*a(n+1)+(-38*n-12*n^2-n^3-36)*a(n+2)+(41+26*n+4*n^2)*a(n+3)+(-17-5*n)*a(n+4)+2*a(n+5), a(4)=18, a(5)=65}
a(n) = A002104(n)-(n-1)!. - Vladeta Jovovic, Apr 03 2005
a(n) ~ (n-1)! * (exp(1)-1). - Vaclav Kotesovec, Sep 29 2013
a(n) = Sum_{k=0..n-2} k! * binomial(n,k+1). - Seiichi Manyama, May 13 2022
MAPLE
spec := [S, {B=Set(Z, 1 <= card), C=Cycle(Z), S=Prod(B, C)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
MATHEMATICA
CoefficientList[Series[Log[-1/(-1+x)]*E^x-Log[-1/(-1+x)], {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Sep 29 2013 *)
PROG
(PARI) my(N=30, x='x+O('x^N)); concat([0, 0], Vec(serlaplace(-log(1-x)*(exp(x)-1)))) \\ Seiichi Manyama, May 13 2022
(PARI) a(n) = sum(k=0, n-2, k!*binomial(n, k+1)); \\ Seiichi Manyama, May 13 2022
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
EXTENSIONS
New name using e.g.f., Joerg Arndt, Sep 30 2013
STATUS
approved