OFFSET
0,4
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 598
FORMULA
E.g.f.: (1-x)/(1-x-x^4+x^5-x^3)
Recurrence: {a(1)=0, a(0)=1, a(2)=0, a(3)=6, a(4)=48, (n^5+15*n^4+274*n+120+85*n^3+225*n^2)*a(n)+(-14*n^3-71*n^2-154*n-120-n^4)*a(n+1)+(-12*n^2-47*n-60-n^3)*a(n+2)+(-5-n)*a(n+4)+a(n+5)=0}
Sum(1/8519*(138+2003*_alpha-346*_alpha^2-444*_alpha^3+11*_alpha^4)*_alpha^(-1-n), _alpha=RootOf(1-_Z-_Z^4+_Z^5-_Z^3))*n!
a(n)= n!*A052532(n). - R. J. Mathar, Nov 27 2011
MAPLE
spec := [S, {S=Sequence(Prod(Z, Z, Z, Union(Z, Sequence(Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
MATHEMATICA
With[{nn=20}, CoefficientList[Series[(1-x)/(1-x-x^3-x^4+x^5), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Apr 27 2014 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
STATUS
approved