1 x 5     = 5    # pattern 1, no prev value so start with 5
5 x 2     = 10   # pattern 2, constant
10 x 2.5  = 25   # pattern 1, prev value 5 / 2
25 x 2    = 50   # pattern 2, constant
50 x 1.25 = 62.5 # pattern 1, prev value 2.5 / 2