%I A093971
%S A093971 0,1,2,7,16,40,86,195,404,873,1795,3727,7585,15537,31368,63582,127933,
%T A093971 257746,517312,1038993,2081696,4173322,8355792,16731799,33484323,
%U A093971 67014365,134069494,268234688,536562699,1073326281
%N A093971 Number of sum-full subsets of {1,...,n}; subsets A such that there is 
               a solution to x+y=z for x,y,z in A.
%C A093971 In sumset notation, number of subsets A of {1,...,n} such that the intersection 
               of A and 2A is nonempty.
%H A093971 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Sum-FreeSet.html">Sum-Free Set</a>
%F A093971 a(n) = 2^n - A007865(n)
%Y A093971 Cf. A007865 (number of sum-free subsets of 1..n).
%Y A093971 Sequence in context: A042243 A041887 A129441 this_sequence A065497 A131727 
               A073371
%Y A093971 Adjacent sequences: A093968 A093969 A093970 this_sequence A093972 A093973 
               A093974
%K A093971 nonn
%O A093971 1,3
%A A093971 T. D. Noe (noe(AT)sspectra.com), Apr 20 2004