# Gruenberger's prime path

hi i'm looking for some historical informations about Gruenberger path. it is a path based on conjecture that every prime could be written in the form $6k+1$ and $6k-1$ (but what is the name of this conjecture?) i don't find a lot in the net.. the best one seems to be this site.. any other infos?

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Every prime.... except 2 and 3. And with this exception is not a conjecture but an essentially obvious fact, see Ross' answer below. –  Andrea Mori Feb 1 '11 at 14:36