164881domain: NPropertiesPrimalityPrimeyesAppears in sequencesPrimes p such that, for p < q < r three consecutive primes, p + 2q + 2r, 2p + q + 2r and 2p + 2q + r are all primes.at n=20A216262Number of subsets of {1..n} whose elements have the same number of prime factors, counted with multiplicity.at n=49A339511Prime numbersat n=15087