Explaination of primes beyond 400: They are a (mostly unrecognizable) combination of the digits in a represenation of them in a random base 3-25 (the base is random to prevent centrism for a certain base, and are not stacked to not make it obvious)
Credits to @RodolfoYT12345 for the idea Also @Danielthenb81 (I got it wrong) and @FlameBlox_The32 might be interested
