The answer will depend on what the series is! And since you have not bothered to provide that crucial bit of information, I cannot provide a more useful answer.
This is the series of square numbers, (16= 4*4). The next number is 5*5=25.
625
481
The series is decreasing by consecutive perfect squares starting from 16^2 (256) and decreasing by 2^2 each time. Therefore, the next number in the series would be 4^2, which is 16.
16*3 = 48
24
26
37
36
Greg Biffle currently drives the #16 car in the Nascar Sprint Cup Series.
22
It is: 16 squared = 256