154390domain: NAppears in sequencesNumber of tilings of a 3 X n rectangle with n trominoes.at n=13A134438Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 1), (0, 0, 1), (1, 0, -1), (1, 1, 0)}.at n=9A150485