06-08-2011, 05:37 PM
257 is called a sexy prime.
Since 257 + 2 = 259, a semiprime, 257 is a Chen prime. It is also an Eisenstein prime with no imaginary part, and a Pierpont prime.
Since 257 + 2 = 259, a semiprime, 257 is a Chen prime. It is also an Eisenstein prime with no imaginary part, and a Pierpont prime.