80611domain: NPropertiesPrimalityPrimeyesAppears in sequencesMiddle of 3 consecutive prime numbers such that p1*p2*p3 + d1 + d2 - 1 = average of twin prime pairs, d1 (delta) = p2 - p1, d2 (delta) = p3 - p2.at n=18A153404Primes where the first digit equals the sum of all the other digits.at n=56A156307Prime numbersat n=7887