The original picture is on the left, with a circumference of 3;
1) After the 1 th increase, as shown in Figure 2, each side actually increased 1/3, so the perimeter also increased1/3; That is, the perimeter after the 1 th growth is the original1+1/3 = 4/3;
2) After the second growth, as shown in Figure 3, each side actually increased by1/3 compared with each side in Figure 2;
So the perimeter after the second growth is1+1/3 = 4/3 after the first growth;
……
By analogy, after growing n times, the circumference is (4/3) n of the original figure;
∴ The circumference after N times increase is: 3 * (4/3) n = 4 n/[3 (n- 1)].