438939648domain: NAppears in sequencesa(1) = 1, a(n) = smallest multiple of a(n-1) > a(n-1) such that a(n) + 1 is a prime.at n=16A084716Trajectory of 3778888999 under "x -> product of digits of x" map.at n=1A121110Trajectory of 277777788888899 under "x -> product of digits of x" map.at n=2A121111