646271domain: NPropertiesPrimalityPrimeyesAppears in sequencesLeast k, 1 <= k <= 2^n, such that the continued fraction for 2^n/k contains the maximum number of elements.at n=19A089636Primes p such that phi(p+1) = phi(phi(p-1)+1).at n=13A271655Prime numbersat n=52543