248639domain: NPropertiesPrimalityPrimeyesAppears in sequencesLower primes p1 in a twin pair such that sum of p1 and p2 yields average a1 of twin prime pairs and product of 2*a1 is another average of twin prime pairs.at n=1A178421Primes of the form 5n^2 - 6.at n=19A201787Prime numbersat n=21933