Find the number of holes, and the triangles that remain at each step of the shape sequence that leads to the Sierpinski Triangle.
At Step 0: Holes = 0 Triangles remaining = 1
At Step 1: Holes = 1 Triangles remaining = 3
At Step 2: Holes = 1 + 3 = 4 Triangles remaining = 9
At Step n: Holes = 1 + 3 + 3² + ... + 3^(n-1) Triangles remaining =
Explanation
The chapter shows that for the Sierpinski Triangle, each remaining triangle gives rise to 3 triangles in the next step (unlike 8 in the Sierpinski Carpet). So R_n = . For holes, each remaining triangle creates one new hole, so H_{n+1} = H_n + R_n, leading to H_n = 1 + 3 + 3² + ... + 3^(n-1).
Solution Steps
Step 1: At Step 0, there is 1 triangle and 0 holes.
Step 2: Each remaining triangle produces 3 new triangles, so R_n = .
Step 3: Each remaining triangle creates 1 new hole, so H_{n+1} = H_n + R_n.
Step 4: Calculate: R_0=1, R_1=3, R_2=9; H_0=0, H_1=1, H_2=1+3=4.
Step 5: General formula: R_n = , H_n = ( - 1)/2 for n 1.