Answer:
See answer below
Step-by-step explanation:
Using structural induction, we would have to prove that 1 and all the numbers derived from this fact, have the property.
That is to say, we would have to prove that
1, 3*1+2, 5*1-1 and 1+7 = {1, 4, 5, 8} have the property we want to prove S has.