The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A075756 Number of hierarchies of hierarchies of hierarchies on n points. 1
1, 1, 6, 52, 588, 8174, 134537, 2554647, 54909468, 1316675221, 34820961457, 1006230148609, 31529224324159, 1064355502971193, 38497326001639439, 1484865225798412485, 60822449267067095601, 2636248249383130776940, 120520100503562054999860, 5794815395039941996204424 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
N. J. A. Sloane and Thomas Wieder, The Number of Hierarchical Orderings, arXiv:math/0307064 [math.CO], 2003; Order 21 (2004), 83-89.
FORMULA
E.g.f.: exp(f(x)-1) where f(x) = e.g.f. for A075744.
MATHEMATICA
m = 20;
f[x_] = E^(-1 + E^(-1 + 1/(2 - E^x)));
CoefficientList[Exp[f[x] - 1] + O[x]^m, x]*Range[0, m - 1]! (* Jean-François Alcover, Feb 24 2019 *)
CROSSREFS
Sequence in context: A355162 A127133 A243249 * A363008 A217486 A144345
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Oct 15 2002
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 26 05:37 EDT 2024. Contains 372807 sequences. (Running on oeis4.)