111149057domain: NPropertiesPrimalityPrimeyesAppears in sequencesa(n) = 2^n*t + 1 where t is the least x such that there exists an r in the range 2 <= r <= x+1 that is coprime to 2^n*x + 1 and has multiplicative order 2^n modulo 2^n*x + 1.at n=20A370879Prime numbersat n=6365238