About this: it will first check if a number is "probably prime" using gmp_prob_prime(). It will then spend up to 1s testing sums of powers, printing any as appropriate.

GCF (greatest common factors) are calculated using my own, probably somewhat / not terribly inefficient algorithm.

There exists a virtual hat, from which one can draw names.
The idea: you add a bunch of names to the hat, and each of those people (virtually) draw a unique name from it. This can be used for a "secret santa" game or similar. Check it out, click an ad.