Thread: "Rare" Primes
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Old 2008-08-29, 14:24   #55
R.D. Silverman
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Nov 2003

22·5·373 Posts

Originally Posted by retina View Post
f(x)=29-x^2 ?
Although not explicitly stated, I believe that the domain is N. Now,
f(x) is prime for x = 0, 4 and no other. If you accept the more general
definition of prime (i.e. not restricted to just N) then f(x) will be prime
i.o. (although a proof is lacking). If we allow x \in R, then f(x) is
indeed prime the required number of times.
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