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%I #7 Mar 30 2012 17:37:34
%S 1,3,6,9,14,17,24,29,36,41,52,57,70,77,86,95,112,119,138,147,160,171,
%T 194,203,224,237,256,269,298,307,338,355,376,393,418,431,468,487,512,
%U 529,570,583,626,647,672,695,742,759,802,823
%N Number of nonempty subsets of {1, 2, ..., n} with <=2 pairwise coprime elements.
%H Alois P. Heinz, <a href="/A187263/b187263.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A187262(n,2).
%e a(4) = 9 because there are 9 nonempty subsets of {1,2,3,4} with <=2 pairwise coprime elements: {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {3,4}.
%Y Column 2 of triangle A187262. First differences are A039649 for n>1.
%K nonn
%O 1,2
%A _Alois P. Heinz_, Mar 07 2011
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