(1) Prompt the user for a beginning and ending number, and print all numbers
    from beginning to ending number by 3 to the screen
    -> Generalize by also prompting the user for the increment
    -> Rewrite so that you use a logical loop rather than a count loop
       (or vice versa)

(2) Prompt user for beginning and ending number.  Calculate the sum of
    all integers between begin and end inclusive.

(3) Prompt user to enter N, the number in the sequence to compute, and
    the initial seed values S0 and S1.  Then, compute and print the Nth
    number in the sequence using the definition:
       S(i) = 100*S(i-2) + S(i-1)
    Note that the () above do not refer to arrays, but subscripts
    (eg., S(i) should be read as Si).
    -> Remember to handle the cases where N is 0 or 1!