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

1,1

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.

Links

Table of n, a(n) for n=1..18.

Dario Alpern, Brilliant numbers

Example

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.

Crossrefs

Cf. A083128.

Sequence in context: A367493 A365845 A292747 * A302277 A302727 A116267

Adjacent sequences: A083179 A083180 A083181 * A083183 A083184 A083185

Keyword

nonn,base

Author

Robert G. Wilson v, May 11 2003

Status

approved