%I A076543
%S A076543 1,3,6,2,7,13,20,12,3,13,24,12,25,39,54,38,55,37,56,36,57,79,102,78,53,
%T A076543 79,52,24,53,83,114,82,115,149,184,148,185,223,262,222,263,305,348,304,
%U A076543 259,305,352,304,255,205,256,204,257,203,258,202,259,317,376,316,377
%N A076543 Sum(k=1 to n) k*sqf(k); sqf(k)=1 if k is squarefree and sqf(k)=-1 otherwise.
%C A076543 Suprisingly, first 12 terms are also in A074170.
%Y A076543 Cf. A074170.
%Y A076543 Sequence in context: A125717 A065232 A074170 this_sequence A005132 A064388 
               A064387
%Y A076543 Adjacent sequences: A076540 A076541 A076542 this_sequence A076544 A076545 
               A076546
%K A076543 easy,nonn
%O A076543 0,2
%A A076543 Zak Seidov (zakseidov(AT)yahoo.com; zakseidov(AT)yahoo.com), Oct 19 2002