Factors of generalized Fermat numbers

Generalized Fermat numbers have the form ${F_{b,m}} = {b^{{2^m}}} + 1$. Their odd prime factors are of the form $k \cdot {2^n} + 1$, k odd, $n > m$. It is shown that each prime is a factor of some ${F_{b,m}}$ for approximately $1/k$ bases b, independent of n. Divisors of generalized Fermat numbers of base 6, base 10, and base 12 are tabulated. Three new factors of standard Fermat numbers are included.