Search: id:A118259
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%I A118259
%S A118259 1,3,7,7,13,17,27,27,27,33,47,47,63,73,85,85,107,107,131,131,147,165,
%T A118259 195,195,195,215,215,215,249,265,303,303,329,355,385,385,431,461,495,
%U A118259 495,547,569,625,625,625,661,721,721,721,721,763,763,827,827,877,877
%N A118259 Numbers of strongly carefree couples (a,b) with a,b<=n.
%H A118259 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               CarefreeCouple.html">Carefree Couple</a>
%F A118259 a(n)=sum_{i,j=1...n}mu(i*j)^2 [From Benoit Cloitre (benoit7848c(AT)orange.fr), 
               Oct 10 2009]
%o A118259 (PARI) a(n)=sum(i=1,n,sum(j=1,n,moebius(i*j)^2)) [From Benoit Cloitre 
               (benoit7848c(AT)orange.fr), Oct 10 2009]
%Y A118259 Cf. A118258, A118260.
%Y A118259 Sequence in context: A073881 A137315 A139795 this_sequence A060845 A060215 
               A059478
%Y A118259 Adjacent sequences: A118256 A118257 A118258 this_sequence A118260 A118261 
               A118262
%K A118259 nonn
%O A118259 1,2
%A A118259 Eric Weisstein (eric(AT)weisstein.com), Apr 20, 2006

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