100999999999domain: NAppears in sequencesPrimes of the form 10^n + 10^(n-2) - 1.at n=4A096210Primes of the form m = 10^i + 10^j - 1, where i > j >= 0.at n=14A239720Primes of the form 10^i + 10^j - 1.at n=19A306855