Answer:
4n + 1
Step-by-step explanation: The numbers are rising by 4, so this gives us 4n. Term number 1: 4n = 4, but the first number in the sequence is 5 so we have to add 1.
Term number 2: 4n = 8, but the second number in the sequence is 9 so, again, we have to add 1.
