Chain emails are emails with a message suggesting you will have good luck if you forward the email on to others.
suppose a student started a chain email by sending the message to 3 friends and asking those friends to each send the
same email to 3 more friends exactly 1 day after receiving it.
a. write an explicit formula for the sequence that models the number of people who receive the email on the nnth
day. (let the first day be the day the original email was sent.) assume everyone who receives the email follows
the directions.