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A083182
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Greatest 3-brilliant number of size n.
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1
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8, 98, 343, 9971, 99937, 912673, 9999707, 99999667, 991026973, 9999999467, 99999999007, 991921850317, 9999999994771, 99999999994117, 999730024299271, 9999999999997097, 99999999999992023, 999949000866995087
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history;
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internal format)
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OFFSET
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1,1
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COMMENTS
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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.
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LINKS
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Table of n, a(n) for n=1..18.
Dario Alpern, Brilliant numbers
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EXAMPLE
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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.
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CROSSREFS
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Cf. A083128.
Sequence in context: A218451 A262777 A292747 * A302277 A302727 A116267
Adjacent sequences: A083179 A083180 A083181 * A083183 A083184 A083185
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KEYWORD
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nonn,base
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AUTHOR
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Robert G. Wilson v, May 11 2003
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STATUS
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approved
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