This is a simple subtraction series in which a random number, 93, is interpolated as every third number. In the subtraction series, 10 is subtracted from each number to arrive at the next.
Here, there are two alternating patterns, with every other number following a different pattern. The first pattern begins with 13 and adds 2 to each number to arrive at the next; the alternating pattern begins with 29 and subtracts 3 each time.
This is a simple subtraction with repetition series. It begins with 20, which is repeated, then 3 is subtracted, resulting in 17, which is repeated, and so on.
EXAMIANS