%I A085721
%S A085721 4,6,9,25,35,49,121,143,169,289,323,361,391,437,493,527,529,551,589,667,
%T A085721 713,841,899,961,1369,1517,1591,1681,1739,1763,1849,1927,1961,2021,2173,
%U A085721 2183,2209,2257,2279,2419,2491,2501,2537,2623,2773,2809
%N A085721 Semiprimes whose prime factors have an equal number of digits in binary 
               representation.
%H A085721 Dario A. Alpern, <a href="http://www.alpertron.com.ar/BRILLIANT.HTM">
               Brilliant Numbers</a>.
%e A085721 A078972(35) = 527 = 17*31 -> 10001*11111, therefore 527 is a term;
%e A085721 A078972(37) = 533 = 13*41 -> 1101*101001, therefore 533 is not a term;
%e A085721 A001358(1920) = 7169 = 67*107 -> 1000011*1101011: therefore 7169 a term, 
               but not of A078972.
%Y A085721 Cf. A078972, A001358, A007088, A070939, A055642.
%Y A085721 Sequence in context: A084994 A046328 A046376 this_sequence A081614 A107665 
               A085733
%Y A085721 Adjacent sequences: A085718 A085719 A085720 this_sequence A085722 A085723 
               A085724
%K A085721 nonn
%O A085721 1,1
%A A085721 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jul 20 2003