1, where n represents the side length of the triangle, and when n is 2, it needs to be matched three times; When n is 2, 9 is required; When n is 3,18 is required; How many matches do you need to put 20 matches on each side? How many matches do you need when X is placed on both sides?

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.