One solution is 316, 584 as the next two numbers by using the formula 43x^2-33x+28 and putting in values of x=0, 1, 2. When x=3 we get 316 and when x=4 we get 584.
Another solution is found by adding 1 to the sum of the first pair of numbers: 28+38=66, 66+1=67, then doubling it: 67*2=134. So, 38+134+1=173, then double it: 346. That gives us 28, 38, 134, 346. 134+346+1=481, then double it: 962. We then get: 28, 38, 134, 346, 962.