A083182 Greatest 3-brilliant number of size n.

8, 98, 343, 9971, 99937, 912673, 9999707, 99999667, 991026973, 9999999467, 99999999007, 991921850317, 9999999994771, 99999999994117, 999730024299271, 9999999999997097, 99999999999992023, 999949000866995087

Offset: 1

Author

Robert G. Wilson v, May 11 2003

Keywords

• nonn
• base

Comments

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.

a(3n) will always be the cube of the greatest prime less than 10^n.

Examples

			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.
		

Links

• Dario Alpern, Brilliant numbers

Crossrefs

Cf. A083128.