Fermat prime

Etymology
.

Noun

 * 1)  A Fermat number that is prime.
 * 2) * 2013, Dean Hathout, Wearing Gauss’s Jersey, Taylor & Francis (CRC Press), page xi,
 * Believe it or not, so far only five Fermat primes are known:
 * F0 = 3, F1 = 5, F2 = 17, F3 = 257, and F4 = 65537.
 * The next 28 Fermat numbers, F5 through F32, are known to be composite.
 * Believe it or not, so far only five Fermat primes are known:
 * F0 = 3, F1 = 5, F2 = 17, F3 = 257, and F4 = 65537.
 * The next 28 Fermat numbers, F5 through F32, are known to be composite.