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 A105586 #5 Mar 30 2012 18:59:06 %S A105586 1,1,1,1,1,1,1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, %T A105586 1,1,0,0,0,0,1,0,0,0,1,0,0,0,0,1,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, %U A105586 1,1,1,1,1,1,1,1,1,1,0,0,0,0,1,0,0,0,1,1,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 %N A105586 A Moebius-binomial triangle. %C A105586 n-th row is all 1's unless n is not squarefree (see A013929). Row sums are A105587. Diagonal sums are A105588. Inverse is A105589. %F A105586 Number triangle T(n, k)=if(k<=n, binomial(abs(mu(n)), abs(mu(k))), 0) %e A105586 Triangle starts %e A105586 1; %e A105586 1,1; %e A105586 1,1,1; %e A105586 1,1,1,1; %e A105586 0,0,0,0,1; %e A105586 1,1,1,1,1,1; %e A105586 1,1,1,1,1,1,1; %e A105586 1,1,1,1,1,1,1,1; %e A105586 0,0,0,0,1,0,0,0,1; %K A105586 easy,nonn,tabl %O A105586 0,1 %A A105586 _Paul Barry_, Apr 14 2005