4443815554domain: NAppears in sequencesNumber of Grand Motzkin paths of length n and having no hills (i.e., no ud's starting at level 0). (A Grand Motzkin path of length n is a path in the half-plane x >= 0, starting at (0,0), ending at (n,0) and consisting of steps u=(1,1), d=(1,-1) and h=(1,0).)at n=23A109192