6216189936domain: NAppears in sequencesLet S(x,y) = number of lattice paths from (0,0) to (x,y) that use the step set { (0,1), (1,0), (2,0), (3,0), ...} and never pass below y = x. Sequence gives S(n-1,n) = number of 'Schröder' trees with n+1 leaves and root of degree 2.at n=15A010683