When choosing the exclusion shells, you only require those that are wholly divisible into 30. Numbers less than the prime being plotted (3 & 2 in this case) don’t need to be included either. So for the 5 shell, the exclusion shells that make the reveal shell work are the 1, 5, 6, 10 & 15 shells.
The 7 shell
- The Reveal shell is 7× 5×3×2×1=210.
- The next prime number is 7...
- So the system works to 11^2=121.