405269domain: NPropertiesPrimalityPrimeyesAppears in sequencesPrimes that remain prime through 4 iterations of function f(x) = 2x + 1.at n=18A023302Primes that remain prime through 5 iterations of function f(x) = 2x + 1.at n=3A023330Initial (unsafe) primes of Cunningham chains of first type with length exactly 6.at n=3A059766Prime numbersat n=34244