332387domain: NAppears in sequencesa(n) = ceiling((3-sqrt(3))*4^(n-3)) + 1 for n>=2, a(1)=1.at n=11A094062a(n) = ceiling((3-sqrt(3))*4^(n-3)) + 1.at n=12A101360Consider the first run of composites that contains at least two numbers whose largest prime factor is prime(n), n >= 2. a(n) is the second of these numbers.at n=17A137800