On Wednesday 14 March 2007 08:58, Daniel Asimov wrote:

Goldbach's conjecture is that every even number >= 4 is the sum of two primes.

But what's known about this question:

<< Is every even number the difference of two primes?

http://primes.utm.edu/notes/conjectures/ Open, but Chen's work shows that every even number is the difference between a prime and a prime-or-pq. I'd accordingly guess that it probably needs the same kind of insights as the twin primes conjecture or Goldbach. -- g