171369

Appears in sequences

• Number of restricted hexagonal polyominoes with n cells.at n=10A002212
• Number of polyhexes with n hexagons, having reflectional symmetry (see Harary and Read for precise definition).at n=19A002215
• a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-2)*a(2) for n >= 3.at n=10A025238
• Catafusenes (see reference for precise definition).at n=19A044044
• Path-counting array T; each step of a path is (1 right) or (1 up) to a point below line y=x, else (1 right and 1 up) or (1 up) to a point on the line y=x, else (1 left) or (1 up) to a point above line y=x. T(i,j)=number of paths to point (i-j,j), for 1<=j<=i, i >= 1.at n=54A055450
• Triangle read by rows: T(n,k) = number of lattice paths from (0,0) to (n,k) that do not go below the line y=0 and consist of steps U=(1,1), D=(1,-1) and three types of steps H=(1,0) (left factors of 3-Motzkin steps).at n=45A091965
• Triangle read by rows: T(n,k) is the number of Schroeder paths of length 2n and having k peaks at odd height.at n=55A101894
• Generalized Riordan array based on the binomial transform of the Fine's numbers A000957.at n=56A187914
• G.f. satisfies A(x) = (1 + x) * (1 + x/A(x)).at n=11A366325