321534781domain: NPropertiesPrimalityPrimeyesAppears in sequencesMarkov numbers satisfying region 5 (x=5) of the equation x^2 + y^2 + z^2 = 3xyz.at n=15A030452Markov numbers that are prime.at n=21A178444Markoff numbers that are powers of one odd prime or twice powers of one odd prime.at n=30A386894Prime numbersat n=17353542