268393domain: NAppears in sequencesBrilliant star numbers: semiprimes of the form 6n^2 - 6n + 1 such that both prime factors have the same number of decimal digits.at n=18A083749Least integer m > 0 with pi(m*n) = phi(m) + phi(n), where pi(.) is the prime-counting function and phi(.) is Euler's totient function.at n=13A247672