Editing Field map encounter mechanics (section)

=== Offset Math ===

You can find the index of any offset value (the number of times you have to overflow stepid and increment offset to get to this offset value) with the following formula:

<pre>
(offset * 197) mod 256
</pre>

so offset 0 has index 0, offset 13 has index 1, offset 177 has index 53, and offset 243 has index 255.

This works because the modular multiplicative inverse of 13 (modulo 256) is 197. Read more about it on wikipedia if you want because math is pretty cool https://en.wikipedia.org/wiki/Modular_multiplicative_inverse