If we look carefully, 1, 5, 9, 13, ... is a number sequence with the first term as 1. The next term is 4 more than the previous number.
First term = 1
Second term = 1 + 4 = 5
Third term = 5 + 4 = 9
Fourth term = 9 + 4 = 13
Fifth term = 13 + 4 = 17
Thus, the next term is 17