417790domain: NAppears in sequencesNumber 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), (0, 1, -1), (0, 1, 0), (1, 0, 1)}.at n=11A149959Number of (n+3) X (n+3) 0..2 matrices with each 4 X 4 subblock idempotent.at n=16A224720