(A) Determine all possible prime numbers f such that each of (f+1)/2 and (f-1)/4 are prime numbers.

(B) What are the possible prime numbers g such that each of (g+1)/4 and (g-1)/2 are prime numbers?

(In reply to re: f and g by K Sengupta)

Indeed, that was sloppy on my part. The argument in (A) that one of the three terms must = 3 allows only one solution, which I gave. But in (B), TWO of the three terms can = 3 and provide valid solutions. If (g+1)/4 = 3 , you get g= 11 as I mentioned, but if instead (g-1)/2=3, that yields g=7, (g+1)/4=2 which is also a solution.

Thanks for pointing out my omission.

Posted by Paul on 2007-08-22 17:55:30