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Old 2010-12-16, 18:43   #5
R.D. Silverman
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Nov 2003

22·5·373 Posts

Originally Posted by R.D. Silverman View Post
I have not verified that the result is true. I will assume that it is.

I will sketch a proof. This result has very little to do with Mersenne

Let Q = (2x)^2 + 3(3y)^2. Q is prime iff this representation is unique.

Now, follow the (standard!) proof that an integer that is 1 mod 4 is prime
iff it is the sum of two squares in a unique way. i.e. --Factor Q over
Q(sqrt(-3)) and observe that you are doing so in a UFD.

Thanks a lot.
I'm stuck. If there is a unique pair (x,y) then Q is prime,however , if Q is composite, then can we assume that there are no (x,y) pairs or should we consider there are 2,3 or more pairs?
Hint: Composition of quadratic forms...
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