1024144482domain: NAppears in sequencesNumber of paths from (0,0) to (3n,0) that stay in the first quadrant, consist of steps u=(2,1), U=(1,2), or d=(1,-1) and do not touch the x-axis, except at the endpoints.at n=10A108424G.f. satisfies A(x) = 1 + x/A(x)*(1 + 1/A(x)).at n=11A364394