Dear Julian, I'm a mathematician for hobby and I was studying the prime numbers looking for some property I came across a nice relationship between the position and the number, so since it seemed not possible that no one had ever highlighted this relationship I wanted to do a search on the internet and so I discovered I had rediscovered the Sieve of Sundaram! If you are interested, I'd like to send you my small study, which if you think fit, could partially supplement your article giving the possible rational of the sieve. Your sincerely Silvio Gabbianelli