Younan

Prime fractals: palindromes, primes and base-10 Euler pseudoprimes

The prime fractal of N/q pairs the first q − 1 decimal digits of N/q around the middle and records their differences. We show that it is a palindrome for every N coprime to q exactly when q is prime, a base-10 Euler pseudoprime, or 99; equivalently, when 10^((q−1)/2) ≡ ±1 (mod q)...