OFFSET
0,6
COMMENTS
Row 2 of A321396, see section 3.2 in O. Bodini et al.
LINKS
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
KEYWORD
nonn
AUTHOR
Peter Luschny, Nov 14 2018
STATUS
approved