%I A088810
%S A088810 0,0,0,0,1,4,6,18,35,84,137,323,591,1313,2033,4360,7406,15581,23682,
%T A088810 49184,84017,171744,259818,528784,853143,1727011,2601181,5243126
%N A088810 Number of subsets of {1, ..., n} that are double-free but not sum-free.
%C A088810 a(n) = A050291(n) - A007865(n) = A088809(n) - A088812(n).
%H A088810 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Double-FreeSet.html">Double-Free Set</a>
%H A088810 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Sum-FreeSet.html">Sum-Free Set</a>
%H A088810 Reinhard Zumkeller, <a href="a088808.txt">Illustration of initial terms</
               a>
%Y A088810 Sequence in context: A026689 A138276 A156096 this_sequence A005199 A107390 
               A051253
%Y A088810 Adjacent sequences: A088807 A088808 A088809 this_sequence A088811 A088812 
               A088813
%K A088810 nonn
%O A088810 0,6
%A A088810 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 19 2003