Radius Number of Pixels

1 4

2 12

3 16

4 24

5 28

6 32

7 40

8 44

9 52

10 56

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**Spoiler:**

It goes up by 4 or 8 for each radius increment but I can't work out the pattern behind it.

2 times the radius, times the square root of 8 is the mean, but it is not precise enough.

I'm hoping someone has a better grasp of the maths involved and can provide a single formula that provides the exact number of pixels required for any given radius. Thanks!