628736domain: NAppears in sequencesNumber of (1,1)-steps in all Delannoy paths of length n.at n=8A108666a(n) = 2*a(n-2) + 4*a(n-3), with initial terms 0, 1, 1.at n=21A134136Number of (n+1) X (3+1) 0..2 arrays colored with the upper median value of each 2 X 2 subblock.at n=20A235949