We have a prime number is 2 or 3 of of the form 6n\pm 1 for n \gt 0 let us compute n^2+2
2^2 + 2 = 6 = 2 * 3 not a prime
3^2+ 2 = 11 is a prime
(6n\pm 1)^2+ 2 = (36n^2 \pm 12 n + 1) + 2 = (36n^2 \pm 12 n + 3) = 3(12n^2 \pm 4 n + 1) which is not a prime
hence 11 is the only prime
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