This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A156241 #4 Mar 30 2012 18:53:09 %S A156241 1,-1,1,-1,0,1,0,0,0,1,-1,0,0,0,1,1,-1,-1,0,0,1,-1,0,0,0,0,0,1,0,0,0, %T A156241 0,0,0,0,1,0,0,0,0,0,0,0,0,1,1,-1,0,0,-1,0,0,0,0,1,-1,0,0,0,0,0,0,0,0, %U A156241 0,1,0,0,0,0,0,0,0,0,0,0,0,1,-1,0,0,0,0,0,0,0,0,0,0,0,1,1,-1,0,0,0,0,-1,0,0 %N A156241 Triangle read by rows, T(n,k). If k divides n then A008683(n)*A008683(k). %C A156241 A008683 is found in the first column. A087003 appears in the second column. %C A156241 The definition does not match the values for n=k. Apparently T(n,n) has been set to 1, not mu(n)*mu(n). [From _R. J. Mathar_, Mar 14 2009] %K A156241 sign,tabl %O A156241 1,1 %A A156241 _Mats Granvik_, Feb 07 2009