OFFSET
1,1
COMMENTS
Jacques Tramu confirmed and extended these results. If all of the unnecessary primes are excluded, all even numbers up to 60000 can be obtained. Not proved, a proof of Goldbach's conjecture would be easier. It would be good to verify the unnecessary list to a million or so. So far, 3/5 of the primes are unnecessary.
LINKS
Ed Pegg Jr, Goldbach's conjecture, Material added 09 April 2005.
EXAMPLE
3 and 5 are necessary for 3+5=8. 7 is necessary for 5+7 = 12. 11 seems to be a completely unnecessary prime, so I marked it as such. 13 is then needed for 5+13 = 18 (can't use 7+11=18, since I've ruled 11 unnecessary). And so on, looking at each prime in turn and determining whether they are necessary or unnecessary.
CROSSREFS
KEYWORD
nonn
AUTHOR
Ed Pegg Jr, Apr 11 2005
STATUS
approved