What program are you running ?
When you wrote Fermat factoring do you mean factoring Fermat numbers ?
If so, then they are numbers such as F5, the fifth Fermat number,
F1 through F4 are prime.
Fermat numbers take the form of 2^2^n + 1
and the factors are of the form k*2^(n+2) + 1.
For example F5 means
2^2^5 + 1 = 2^32 + 1 = 4294967296 + 1 = 4294967297.
and potential factors are k*2^(5+2) + 1 = k*2^7 + 1 = k*128 + 1
with k taking the values 1 through 33554432, 33554432 = 2^25 = 2^(327).
It has been factored, of which two factors are
5*2^7 + 1 = 5*128 + 1 = 641
52347*2^7 + 1 = 52347*128 + 1 = 6700416 + 1 = 6700417
641 * 6700417 = 4294967297.
