55555777domain: NPropertiesPrimalityPrimeyesAppears in sequencesPrimes that contain digits 5 and 7 only.at n=28A020467Smallest n-digit prime containing only the digits 5 and 7, or 0 if no such prime exists.at n=7A036946Primes whose digits do not appear in three previous terms.at n=31A107367Prime numbersat n=3313348