227627domain: NPropertiesPrimalityPrimeyesAppears in sequencesPrimes p such that 54*p-1, 54*p+1 and 60*p-1, 60*p+1 are twin primes.at n=18A138698Primes having only {2, 6, 7} as digits.at n=34A385787Prime numbersat n=20237