OFFSET
0,2
REFERENCES
Recski, A.; Enumerating partitional matroids. Stud. Sci. Math. Hungar. 9 (1974), 247-249 (1975).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
T. D. Noe, Table of n, a(n) for n = 0..100
A. Recski, Enumerating partitional matroids, Preprint.
A. Recski & N. J. A. Sloane, Correspondence, 1975
FORMULA
E.g.f.: exp( (x-1)*exp(x) + 2*x + 1 ).
a(n) = Sum_{j=0..n} binomial(n, j) * 2^(n-j) * A327006(j+1). - G. C. Greubel, Nov 16 2022
MATHEMATICA
With[{nn=30}, CoefficientList[Series[Exp[(x-1)E^x+2x+1], {x, 0, nn}], x]Range[0, nn]!] (* Harvey P. Dale, Nov 22 2012 *)
PROG
(Magma) R<x>:=PowerSeriesRing(Rationals(), 40); Coefficients(R!(Laplace( Exp((x-1)*Exp(x) + 2*x + 1) ))); // G. C. Greubel, Nov 16 2022
(SageMath)
def A005387_list(prec):
P.<x> = PowerSeriesRing(QQ, prec)
return P( exp((x-1)*exp(x) + 2*x + 1) ).egf_to_ogf().list()
A005387_list(40) # G. C. Greubel, Nov 16 2022
CROSSREFS
KEYWORD
nonn,easy,nice
AUTHOR
EXTENSIONS
More terms from James Sellers, Aug 21 2000
STATUS
approved