176289domain: NAppears in sequencesNumber of B-trees of order 3 with n leaves.at n=33A0145354-step Fibonacci sequence starting with 1, 1, 0, 1.at n=21A251704Number of nX2 0..1 arrays with every element unequal to 1, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.at n=9A318062