One week you tell 3 of your friends a secret. The next week, each of them tells 3 people the secret and the
next week each of those people tell 3 more people. So the first week, 3 new people know the secret, the
second week 9 new people know the secret, the third week 27 new people know the secret, etc. How many
people find out the secret on the 7th week?