cp's OEIS Frontend

A127627 Triangle T(n,k) = A054525(n,k)*A018804(k), read by rows 1<=k<=n.

%I A127627 #10 Oct 21 2012 14:37:14
%S A127627 1,-1,3,-1,0,5,0,-3,0,8,-1,0,0,0,9,1,-3,-5,0,0,15,-1,0,0,0,0,0,13,0,0,
%T A127627 0,-8,0,0,0,20,0,0,-5,0,0,0,0,0,21,1,-3,0,0,-9,0,0,0,0,27,-1,0,0,0,0,
%U A127627 0,0,0,0,0,21,0,3,0,-8,0,-15,0,0,0,0,0,40
%N A127627 Triangle T(n,k) = A054525(n,k)*A018804(k), read by rows 1<=k<=n.
%F A127627 T(n,1) = A008683(n).
%F A127627 T(n,n) = A018804(n).
%e A127627 First few rows of the triangle are:
%e A127627 1;
%e A127627 -1, 3;
%e A127627 -1, 0, 5;
%e A127627 0, -3, 0, 8;
%e A127627 -1, 0, 0, 0, 9;
%e A127627 1, -3,-5, 0, 0, 15;
%e A127627 ...
%p A127627 A018804 := proc(n)
%p A127627     sum(igcd(n, j), j=1..n):
%p A127627 end proc:
%p A127627 A127627 := proc(n,k)
%p A127627     A054525(n,k)*A018804(k) ;
%p A127627 end proc: # _R. J. Mathar_, Oct 21 2012
%Y A127627 Cf. A054525, A018804, A029935 (row sums).
%K A127627 tabl,easy,sign
%O A127627 1,3
%A A127627 _Gary W. Adamson_, Jan 20 2007