When I first learned C, I wrote a program to check the Goldbach conjecture (every even number >= 4 can be shown to be the sum of two prime numbers). For a while

When I first learned C, I wrote a program to check the Goldbach conjecture (every even number >= 4 can be shown to be the sum of two prime numbers). For a while this was the first nontrivial program I would write in any programming language I learned, but in retrospect it was pretty pointless on several levels. It is a good project though, to learn about high performance arithmetic, data structures and has good potential for parallel implementations (I eventually rewrote it on top of PVM to run on a cluster of computers).