Mersenne: Another question about ECM

[Tobias]

Hi and thank you mr Leyland for the reply I have another question. If you are doing ECM factoring on a Fermat number with prime95 should you check the "Factor 2^N+1" box, since "Every factor of a Fermat number fermat(n) has the form 2^(n+2) * k + 1, k >= 2"?   Best Regards, Tobias