%I #14 Jun 05 2023 07:08:14
%S 1,3,-1,4,0,-1,7,-3,0,0,6,0,0,0,-1,12,-4,-3,0,0,1,8,0,0,0,0,0,-1,15,
%T -7,0,0,0,0,0,0,13,0,-4,0,0,0,0,0,0,18,-6,0,0,-3,0,0,0,0,1,12,0,0,0,0,
%U 0,0,0,0,0,-1,28,-12,-7,0,0,3,0,0,0,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,-1
%N Triangle read by rows: A051731 * A143239.
%C Left border = sigma(n), A000203.
%C Right border = mu(n), A008683.
%C Row sums = n.
%C It appears that T(n,k) = Sum_{d|n} mu(d)*sigma(n/d). - _Joerg Arndt_, Jul 31 2011
%e First few rows of the triangle:
%e 1;
%e 3, -1;
%e 4, 0, -1;
%e 7, -3, 0, 0;
%e 6, 0, 0, 0, -1;
%e 12, -4, -3, 0, 0, 1;
%e 8, 0, 0, 0, 0, 0, -1;
%e 15, -7, 0, 0, 0, 0, 0, 0;
%e 13, 0, -4, 0, 0, 0, 0, 0, 0;
%e 18, -6, 0, 0, -3, 0, 0, 0, 0, 1;
%e ...
%Y Cf. A000203, A008683, A051731, A143239.
%K tabl,sign
%O 1,2
%A _Gary W. Adamson_, Aug 07 2008
%E a(68) = -12 corrected by _Georg Fischer_, Jun 05 2023