It is possible to use shortcuts to calculate the index.

However, it is not practical to use shortcuts to go through the process of determining the prime number, calculating the primitive root, and getting to the result, as each action takes a very very long time.

Therefore, I make a table in advance and use it.

We use a dictionary which is written in plist format beforehand.

For my convenience, the available prime numbers are from 5 to 97.