%I A110924
%S A110924 1,2,4,5,7,11,13,17,19,23,25,29,31,37,3,9,35,15,21,41,27,33,43,39,45,47,
%T A110924 49,53,55,59,61,67,51,57,65,63,69,71,73,77,79,83,85,89,91,97,75,81,95,
%U A110924 87,93,101,99,103,105,107,109,113,115,119,121,127,111,117,125,123,129
%N A110924 a(1) = 1, a(2) = 2. a(n) is smallest positive integer not among earlier 
               terms of the sequence where GCD(a(n),a(n-1)+a(n-2)) = 1.
%C A110924 2 and 4 are the only even terms in the sequence. Is every odd positive 
               integer in the sequence?
%H A110924 Leroy Quet, <a href="http://www.prism-of-spirals.net/">Home Page</a> 
               (listed in lieu of email address)
%e A110924 Of the positive integers not among the first 4 terms of the sequence, 
               7 is the smallest which is coprime to a(3) + a(4) = 4 + 5 = 9.
%o A110924 (PARI) { u=[2,1]; c=3; s=u[1]+u[2]; m=Set(); m=setunion(m,[1]); m=setunion(m,
               [2]); print1(1,",",2); for(k=1,100, i=2;while(gcd(i,s)>1 || setsearch(m,
               i)!=0,i++); u[(c%2)+1] = i; c++; s=u[1]+u[2]; m=setunion(m,[i]); 
               print1(i,",")) } (Klasen)
%Y A110924 Sequence in context: A056527 A147991 A033160 this_sequence A028289 A039673 
               A097581
%Y A110924 Adjacent sequences: A110921 A110922 A110923 this_sequence A110925 A110926 
               A110927
%K A110924 nonn
%O A110924 1,2
%A A110924 Leroy Quet Sep 23 2005
%E A110924 More terms from Lambert Klasen (lambert.klasen(AT)gmx.net), Oct 25 2005