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A046442 Semiprimes whose two prime factors are distinct in length. 1

%I #20 Jul 29 2022 05:55:46

%S 22,26,33,34,38,39,46,51,55,57,58,62,65,69,74,77,82,85,86,87,91,93,94,

%T 95,106,111,115,118,119,122,123,129,133,134,141,142,145,146,155,158,

%U 159,161,166,177,178,183,185,194,201,202,203,205,206,213,214,215,217

%N Semiprimes whose two prime factors are distinct in length.

%C Semiprimes (A001358) that are not brilliant numbers (A078972). - _Bernard Schott_, Jul 29 2022

%e 203 because 203 = 7 * 29, which have 1 and 2 digits, respectively.

%t Take[Union[Times@@@Select[Subsets[Prime[Range[50]],{2}],IntegerLength[#[[1]]]!=IntegerLength[#[[2]]]&]],60] (* _Harvey P. Dale_, Dec 29 2010 *)

%Y Equals A001358 \ A078972.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Jul 15 1998

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Last modified April 24 14:09 EDT 2024. Contains 371960 sequences. (Running on oeis4.)