%N Greatest 3-brilliant number of size n.
%C Brilliant numbers, as defined by Peter Wallrodt, are numbers with two prime factors of the same length (in decimal notation). These numbers are generally used for cryptographic purposes and for testing the performance of prime factoring programs.
%C a(3n) will always be the cube of the greatest prime less than 10^n.
%H Dario Alpern, <a href="http://www.alpertron.com.ar/BRILLIANT.HTM">Brilliant numbers</a>
%e a(5) = 99937 = 37 * 37 * 73 and there is no greater number of five digits which has three prime factors, not necessarily different, of the same size in decimal notation.
%Y Cf. A083128.
%A _Robert G. Wilson v_, May 11 2003