1000099999domain: NAppears in sequencesPrimes of the form 10^n + 10^(n-4) - 1.at n=1A096212Primes of the form m = 10^i + 10^j - 1, where i > j >= 0.at n=9A239720Primes of the form 10^i + 10^j - 1.at n=14A306855a(n) is the n-digit number k such that R(k)/k is maximal for any n-digit number.at n=9A372010