376976720745domain: NAppears in sequencesNumber of distributive lattices; also number of paths with n turns when light is reflected from 4 glass plates.at n=25A006357Top line of 4-wave sequence A038197, also bisection of A006357.at n=13A038225Expansion of x - 1/(x - 1/(x - 1/(x - 1/(x + 1)))).at n=25A373568