%I A066724
%S A066724 1,2,3,4,5,7,9,11,13,16,17,19,23,25,29,30,31,37,41,43,47,49,53,59,61,
%T A066724 67,71,73,79,81,83,84,89,97,101,103,107,109,113,121,127,128,131,137,
%U A066724 139,149,151,154,157,163,167,169,173,179,180,181,191,193,197,199,211
%N A066724 a(1) = 1, a(2) = 2; for n > 1, a(n) is the least integer > a(n-1) such 
               that the products a(i)*a(j) for 1 <= i < j <= n are all distinct.
%C A066724 The first 15 terms are the same as A026477; the first 13 terms are the 
               same as A026416.
%e A066724 a(7) is not 10 because we already have 10 = 2*5. Of course all primes 
               appear. a(14) is not 24 because if it was there would be a repeat 
               among the terms a(i)*a(j) for 1 <= i < j <= 14, namely 3*16 = 2*24.
%Y A066724 Cf. A000028, A026477, A026416, A050376, A084400.
%Y A066724 Cf. A080431.
%Y A066724 Sequence in context: A000028 A026416 A123193 this_sequence A079851 A089237 
               A009087
%Y A066724 Adjacent sequences: A066721 A066722 A066723 this_sequence A066725 A066726 
               A066727
%K A066724 easy,nonn
%O A066724 1,2
%A A066724 Robert E. Sawyer (rs.1(AT)mindspring.com), Jan 18 2002