%I A103607
%S A103607 4,6,9,10,14,15,21,22,25,26,33,34,35,38,39,49,51,55,57,58,62,65,74,77,
%T A103607 82,85,86,87,91,93,94,95,106,111,115,118,119,121,122,123,129,133,134,
%U A103607 141,142,143,145,146,155,158,159,161,166,169,177,178,183,185,187
%N A103607 Write down the semiprimes but omit any semiprime (such as 46 or 69) that 
               has appeared as a string earlier in the sequence.
%C A103607 The complement of this sequence is the sequence of semiprimes which are 
               concatenations of successive semiprimes.
%e A103607 46 is not in this sequence because concatenate(A001358(1),A001358(2)) 
               = 46 = 2 * 23.
%e A103607 69 is not in this sequence because concatenate(A001358(2),A001358(3)) 
               = 69 = 3 * 23.
%e A103607 469 is not in this sequence because concatenate(A001358(1),A001358(2),
               A001358(3)) = 469 = 7 * 67.
%e A103607 1415 is not in this sequence because concatenate(A001358(5),A001358(6)) 
               = 1415 = 5 * 283.
%e A103607 2122 is not in this sequence because concatenate(A001358(7),A001358(8)) 
               = 2122 = 2 * 1061.
%e A103607 3839 is not in this sequence because concatenate(A001358(14),A001358(15)) 
               = 3839 = 11 * 349.
%e A103607 469101415 is not in this sequence because concatenate(A001358(1),A001358(2),
               A001358(3),A001358(4)),A001358(5),A001358(6)) = 469101415 = 5 * 93820283.
%Y A103607 Cf. A001358, A048991, A119615.
%Y A103607 Sequence in context: A001358 A108764 A129336 this_sequence A108574 A157931 
               A046368
%Y A103607 Adjacent sequences: A103604 A103605 A103606 this_sequence A103608 A103609 
               A103610
%K A103607 base,easy,nonn
%O A103607 1,1
%A A103607 Jonathan Vos Post (jvospost3(AT)gmail.com), Jun 07 2006