2. In a set of graphs composed of equal circles, 1 graph is composed of 1 circle, the second graph is composed of 3 circles (forming a triangle), and the third graph is composed of 6 circles (forming a triangle) ... If arranged according to this rule, 17 graph is composed of _ _ _ _ _ _.
3. In a 5*5 grid, there are () different walks between two non-adjacent diagonals.