2. After that, 9 people were infected with 2 people each, so the number of infected people was 9×2= 18, and the number of patients at this time was 9+ 18=27.

3. After that, 27 people were infected with 2 people each, so the number of infected people was 27×2=54, and the number of patients at this time was 27+54=8 1.

4. Go down in turn in the above way to get the desired value.