Prime numbers have found a wide application in science. Recently use has been made of a 24 prime number spiral that can apparently be linked to the periodicity of atomic matter as well as to structures in the universe. In many of these conjectures as well as proofs such as that of the abc conjecture one starts from prime numbers greater than or equal to 5 (i.e. all prime numbers, except 2 and 3, can be written in the form 6n+-1). Is there a simple reason for this?
http://www.sciencedirect.com/science/article/pii/S1463018404000061