So I'm looking at 8 increments between 0 (Hex 00) and 255 (Hex FF)... except that there's really 9 because of numbering starting at 0... adding 32 (256/8 = 32) each time worked a treat... especially when I knocked the 1 off of each result:
0 | 00 |
31 | 1F |
63 | 3F |
95 | 5F |
127 | 7F |
159 | 9F |
191 | BF |
223 | DF |
255 | FF |
Which allowed me to create this PNG image via SVG: