login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A007855 Infima closed sets in rooted plane trees on n nodes. 0

%I

%S 1,3,13,63,326,1769,9964,57843,344203,2090470,12912988,80899801,

%T 512896540,3284651548,21217493460,138080484819,904454380446,

%U 5958186674879,39448465279220,262359379484522,1751912981641794,11741044418866476

%N Infima closed sets in rooted plane trees on n nodes.

%H M. Klazar, <a href="http://dx.doi.org/10.1006/eujc.1995.0095">Twelve countings with rooted plane trees</a>, European Journal of Combinatorics 18 (1997), 195-210; Addendum, 18 (1997), 739-740.

%H <a href="/index/Ro#rooted">Index entries for sequences related to rooted trees</a>

%F G.f.: (1/4) * (1 + sqrt(1-4*x)) * (1 - sqrt(3 - 2 / sqrt(1-4*x))) [from Klazar]. - _Sean A. Irvine_, Feb 06 2018

%o (PARI) my(x='x+O('x^30)); Vec((1/4) * (1+sqrt(1-4*x)) * (1-sqrt(3-2/sqrt(1-4*x)))) \\ _Michel Marcus_, Apr 05 2019

%K nonn,changed

%O 1,2

%A _Martin Klazar_

%E More terms from _Sean A. Irvine_, Feb 06 2018

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 18 14:35 EDT 2019. Contains 322209 sequences. (Running on oeis4.)