Problems & Puzzles: Conjectures

Conjecture 2. Chen's Conjecture

"Chen's work mentioned in the discussion of the Goldbach conjecture also showed that every even number is the difference between a prime and a P2." Note : P2 is "a number with no more than two prime factors"



Paul Jobling wrote (20/12/2000): "Chen actually proved this!".


Why I posed this as a conjecture? To tell the truth I don't remember now. Maybe because the Chen's proof is only valid "...for every sufficiently large even number...", according to p. 297, Ribbenboim's well known book? Any help from the readers?


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