6187457domain: NPropertiesPrimalityPrimeyesAppears in sequencesPrimes p for which the period of 1/p is a power of 2.at n=21A072982Irregular triangle read by rows: row n lists the distinct prime factors of the generalized Fermat number F_n(10) = 10^(2^n) + 1.at n=13A391444Prime numbersat n=424837