22280372247domain: NAppears in sequencesNumber of walks of length 2n on the 3-regular tree beginning and ending at some fixed vertex.at n=13A089022Expansion of c(2*x^2)/(1-x*c(2*x^2)), where c(x) = (1-sqrt(1-4*x))/(2*x) is the g.f. of the Catalan numbers (A000108).at n=26A126087