20381027domain: NPropertiesPrimalityPrimeyesAppears in sequencesLargest prime factor of 3^(2n+1) - 1.at n=14A002591Largest prime factor of 3^n - 1.at n=28A074477List of primitive prime divisors of the numbers (3^k-1)/2 (A003462) for k>=2, in order of their occurrence.at n=40A129733Largest prime factor of 9^n - 1.at n=28A274909Prime numbersat n=1293236