118876domain: NAppears in sequencesNumber of polypons with n cells.at n=19A057784G.f. satisfies: A(x) = C(x)*A(x^3*C(x)^4), where C(x) is the g.f. of the Catalan numbers (A000108).at n=11A120900Number of concave kites (darts or arrowheads) on an n X n grid (or geoboard).at n=13A173502