OFFSET
0,2
REFERENCES
Mireille Bousquet-Mélou and Gilles Schaeffer, Counting walks on the slit plane (extended abstract). Mathematics and computer science (Versailles, 2000), 101-112, Trends Math., Birkhäuser, Basel, 2000.
LINKS
M. Bousquet-Mélou and Gilles Schaeffer, Walks on the slit plane, Probability Theory and Related Fields, Vol. 124, no. 3 (2002), 305-344.
FORMULA
G.f.: ((1+sqrt(1+4*t))^(1/2)*(1+sqrt(1-4*t))^(1/2))/(2*(1-4*t)^(3/4)).
MATHEMATICA
CoefficientList[ Sqrt[(1+Sqrt[1-4*t])*(1+Sqrt[1+4*t])]/(2*(1-4*t)^(3/4))+O[t]^30, t] (* Jean-François Alcover, Jun 19 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Mireille Bousquet-Mélou, Mar 27 2000
STATUS
approved