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!)
A321572 Related to the set of Motzkin trees where all leaves are at the same unary height 2. 1
0, 1, 0, 1, 1, 3, 2, 9, 7, 27, 25, 85, 86, 287, 296, 975, 1065, 3369, 3825, 11887, 13836, 42389, 50597, 152549, 186186, 554103, 688494, 2027304, 2559958, 7461971, 9561298, 27617581, 35846863, 102707431, 134874639, 383561963, 509090498, 1437822479, 1927045425 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

COMMENTS

Row 2 of A321396, see section 3.2 in O. Bodini et al.

LINKS

Table of n, a(n) for n=0..38.

Olivier Bodini, Danièle Gardy, Bernhard Gittenberger, Zbigniew Gołębiewski, On the number of unary-binary tree-like structures with restrictions on the unary height, arXiv:1510.01167v1 [math.CO], 2015.

FORMULA

G.f.: (1 - sqrt(1 - 2*z + 2*z*sqrt(1 - 2*z + 2*z*sqrt(1 - 4*z^2))))/(2*z^3).

MAPLE

gf := -(sqrt(2*z*(sqrt(2*z*(sqrt(1-4*z^2)-1)+1)-1)+1)-1)/(2*z^3):

series(gf, z, 44): seq(coeff(%, z, n), n=0..38);

MATHEMATICA

CoefficientList[(1 - Sqrt[2 Sqrt[2 Sqrt[1 - 4z^2] z - 2z + 1] z - 2z + 1])/ (2z^3) + O[z]^40, z] (* Jean-François Alcover, Jun 03 2019 *)

CROSSREFS

Cf. A321396.

Sequence in context: A237651 A124003 A159588 * A118045 A276023 A268822

Adjacent sequences:  A321569 A321570 A321571 * A321573 A321574 A321575

KEYWORD

nonn

AUTHOR

Peter Luschny, Nov 14 2018

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 August 7 23:50 EDT 2022. Contains 355995 sequences. (Running on oeis4.)