Kenneth Hammond
4 Capistrano Pl
Chico, CA 95973
United States

weregoose@gmail.com

After numbers get reflected about their units place, they undergo a Fermat (base 2) probable-prime test, which is made more rugged by a sparser search space dedicated to odd-length, odd-valued (sans fives), palindromic candidates only. Among these and via the algorithm employed, the only theoretical false-positive ("Poulet number") with fewer than a minimum of 13 digits is 1837381; since it would occupy position 266, the program can be instructed ahead of time to seek out another entry if this imitator is to be encountered.

The likes of 2^352 (seen in verification of the 12th palindromic prime) are expected and would inevitably suffer from overflow if not for their elegant reduction a la modular exponentiation; the implementation here has been adapted to skip the least significant bit as per the obvious parity constraint, which at the same time permits a scan through the binary expansion of P itself in lieu of the textbook-prescribed P-1 -- with P ever odd, the subtrahend (or dismissal thereof) has no possibility of derailing the relevant bits.

This submission is in TI-BASIC, and is known to be compatible with TI-OS versions 1.12 and 2.21 (83+ and 84+SE). Thank you so much for hosting!