Recall that a bit string is a string of 0s and 1s. a. (10 pts) Find a recurrence relation for the total number of bit strings of length n that do not have four consecutive 1s. You will earn less than half-credit if you do not include an explanation. b. (5 pts) What are the initial conditions: a0,,a4 ? c. (5 pts) How many bit strings of length 9 do not have four consecutive 1 s