OFFSET
0,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 649
FORMULA
E.g.f.: (1+x^5-x^6)/(1-x).
a(n+1) = (n+1)*a(n), for n > 5.
a(n) = n! + 5!*[n=5].
MAPLE
spec := [S, {S=Union(Sequence(Z), Prod(Z, Z, Z, Z, Z))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
MATHEMATICA
With[{nn=20}, CoefficientList[Series[(1+x^5-x^6)/(1-x), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Feb 04 2014 *)
Table[n! + 5!*Boole[n==5], {n, 0, 40}] (* G. C. Greubel, May 31 2022 *)
PROG
(SageMath) [factorial(n) + factorial(5)*bool(n==5) for n in (0..30)] # G. C. Greubel, May 31 2022
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
STATUS
approved